diff --git a/core/includes/file.inc b/core/includes/file.inc
index 3e5eb8c..4f6f4ca 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -368,7 +368,7 @@ function file_save_htaccess($directory, $private = TRUE, $force_overwrite = FALS
   }
   else {
     $variables = array('%directory' => $directory, '@htaccess' => $htaccess_lines);
-    \Drupal::logger('security')->error("Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <pre><code>@htaccess</code></pre>", $variables);
+    \Drupal::logger('security')->error("Security warning: Could not write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <pre><code>@htaccess</code></pre>", $variables);
     return FALSE;
   }
 }
diff --git a/core/lib/Drupal/Component/Diff/Diff.php b/core/lib/Drupal/Component/Diff/Diff.php
index 1e02ec1..f8be7c2 100644
--- a/core/lib/Drupal/Component/Diff/Diff.php
+++ b/core/lib/Drupal/Component/Diff/Diff.php
@@ -137,18 +137,18 @@ public function closing() {
    */
   public function check($from_lines, $to_lines) {
     if (serialize($from_lines) != serialize($this->orig())) {
-      trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
+      trigger_error("Reconstructed original does not match", E_USER_ERROR);
     }
     if (serialize($to_lines) != serialize($this->closing())) {
-      trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
+      trigger_error("Reconstructed closing does not match", E_USER_ERROR);
     }
 
     $rev = $this->reverse();
     if (serialize($to_lines) != serialize($rev->orig())) {
-      trigger_error("Reversed original doesn't match", E_USER_ERROR);
+      trigger_error("Reversed original does not match", E_USER_ERROR);
     }
     if (serialize($from_lines) != serialize($rev->closing())) {
-      trigger_error("Reversed closing doesn't match", E_USER_ERROR);
+      trigger_error("Reversed closing does not match", E_USER_ERROR);
     }
 
 
diff --git a/core/lib/Drupal/Core/Archiver/ArchiveTar.php b/core/lib/Drupal/Core/Archiver/ArchiveTar.php
index 24085ce..ed3d752 100644
--- a/core/lib/Drupal/Core/Archiver/ArchiveTar.php
+++ b/core/lib/Drupal/Core/Archiver/ArchiveTar.php
@@ -250,7 +250,7 @@ public function __construct($p_tarname, $p_compress = null)
             }
             if (!extension_loaded($extname)) {
                 $this->_error(
-                    "The extension '$extname' couldn't be found.\n" .
+                    "The extension '$extname' could not be found.\n" .
                     "Please make sure your version of PHP was built " .
                     "with '$extname' support.\n"
                 );
diff --git a/core/lib/Drupal/Core/Config/Schema/ArrayElement.php b/core/lib/Drupal/Core/Config/Schema/ArrayElement.php
index c787a4b..f8fb496 100644
--- a/core/lib/Drupal/Core/Config/Schema/ArrayElement.php
+++ b/core/lib/Drupal/Core/Config/Schema/ArrayElement.php
@@ -76,7 +76,7 @@ public function get($name) {
       return $element;
     }
     else {
-      throw new \InvalidArgumentException("The configuration property $name doesn't exist.");
+      throw new \InvalidArgumentException("The configuration property $name does not exist.");
     }
   }
 
diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
index c1fe407..4a03e9c 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -373,7 +373,7 @@ protected function createKeySql($fields) {
 
   public function renameTable($table, $new_name) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table does not exist.", array('@table' => $table, '@table_new' => $new_name)));
     }
     if ($this->tableExists($new_name)) {
       throw new SchemaObjectExistsException(t("Cannot rename @table to @table_new: table @table_new already exists.", array('@table' => $table, '@table_new' => $new_name)));
@@ -394,7 +394,7 @@ public function dropTable($table) {
 
   public function addField($table, $field, $spec, $keys_new = array()) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table doesn't exist.", array('@field' => $field, '@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table does not exist.", array('@field' => $field, '@table' => $table)));
     }
     if ($this->fieldExists($table, $field)) {
       throw new SchemaObjectExistsException(t("Cannot add field @table.@field: field already exists.", array('@field' => $field, '@table' => $table)));
@@ -433,7 +433,7 @@ public function dropField($table, $field) {
 
   public function fieldSetDefault($table, $field, $default) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` SET DEFAULT ' . $this->escapeDefaultValue($default));
@@ -441,7 +441,7 @@ public function fieldSetDefault($table, $field, $default) {
 
   public function fieldSetNoDefault($table, $field) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` DROP DEFAULT');
@@ -456,7 +456,7 @@ public function indexExists($table, $name) {
 
   public function addPrimaryKey($table, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table doesn't exist.", array('@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table does not exist.", array('@table' => $table)));
     }
     if ($this->indexExists($table, 'PRIMARY')) {
       throw new SchemaObjectExistsException(t("Cannot add primary key to table @table: primary key already exists.", array('@table' => $table)));
@@ -476,7 +476,7 @@ public function dropPrimaryKey($table) {
 
   public function addUniqueKey($table, $name, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->indexExists($table, $name)) {
       throw new SchemaObjectExistsException(t("Cannot add unique key @name to table @table: unique key already exists.", array('@table' => $table, '@name' => $name)));
@@ -499,7 +499,7 @@ public function dropUniqueKey($table, $name) {
    */
   public function addIndex($table, $name, $fields, array $spec) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->indexExists($table, $name)) {
       throw new SchemaObjectExistsException(t("Cannot add index @name to table @table: index already exists.", array('@table' => $table, '@name' => $name)));
@@ -522,7 +522,7 @@ public function dropIndex($table, $name) {
 
   public function changeField($table, $field, $field_new, $spec, $keys_new = array()) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field doesn't exist.", array('@table' => $table, '@name' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field does not exist.", array('@table' => $table, '@name' => $field)));
     }
     if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
       throw new SchemaObjectExistsException(t("Cannot rename field @table.@name to @name_new: target field already exists.", array('@table' => $table, '@name' => $field, '@name_new' => $field_new)));
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
index d12788f..6ff9bc5 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
@@ -517,7 +517,7 @@ public function dropTable($table) {
 
   public function addField($table, $field, $spec, $new_keys = array()) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table doesn't exist.", array('@field' => $field, '@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table does not exist.", array('@field' => $field, '@table' => $table)));
     }
     if ($this->fieldExists($table, $field)) {
       throw new SchemaObjectExistsException(t("Cannot add field @table.@field: field already exists.", array('@field' => $field, '@table' => $table)));
@@ -561,7 +561,7 @@ public function dropField($table, $field) {
 
   public function fieldSetDefault($table, $field, $default) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $default = $this->escapeDefaultValue($default);
@@ -571,7 +571,7 @@ public function fieldSetDefault($table, $field, $default) {
 
   public function fieldSetNoDefault($table, $field) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN "' . $field . '" DROP DEFAULT');
@@ -619,7 +619,7 @@ public function constraintExists($table, $name) {
 
   public function addPrimaryKey($table, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table doesn't exist.", array('@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table does not exist.", array('@table' => $table)));
     }
     if ($this->constraintExists($table, 'pkey')) {
       throw new SchemaObjectExistsException(t("Cannot add primary key to table @table: primary key already exists.", array('@table' => $table)));
@@ -641,7 +641,7 @@ public function dropPrimaryKey($table) {
 
   function addUniqueKey($table, $name, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->constraintExists($table, $name . '__key')) {
       throw new SchemaObjectExistsException(t("Cannot add unique key @name to table @table: unique key already exists.", array('@table' => $table, '@name' => $name)));
@@ -666,7 +666,7 @@ public function dropUniqueKey($table, $name) {
    */
   public function addIndex($table, $name, $fields, array $spec) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->indexExists($table, $name)) {
       throw new SchemaObjectExistsException(t("Cannot add index @name to table @table: index already exists.", array('@table' => $table, '@name' => $name)));
@@ -688,7 +688,7 @@ public function dropIndex($table, $name) {
 
   public function changeField($table, $field, $field_new, $spec, $new_keys = array()) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field doesn't exist.", array('@table' => $table, '@name' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field does not exist.", array('@table' => $table, '@name' => $field)));
     }
     if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
       throw new SchemaObjectExistsException(t("Cannot rename field @table.@name to @name_new: target field already exists.", array('@table' => $table, '@name' => $field, '@name_new' => $field_new)));
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
index 1fb1f16..f8394a5 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
@@ -254,7 +254,7 @@ public function getFieldTypeMap() {
 
   public function renameTable($table, $new_name) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table does not exist.", array('@table' => $table, '@table_new' => $new_name)));
     }
     if ($this->tableExists($new_name)) {
       throw new SchemaObjectExistsException(t("Cannot rename @table to @table_new: table @table_new already exists.", array('@table' => $table, '@table_new' => $new_name)));
@@ -300,7 +300,7 @@ public function dropTable($table) {
 
   public function addField($table, $field, $specification, $keys_new = array()) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table doesn't exist.", array('@field' => $field, '@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table does not exist.", array('@field' => $field, '@table' => $table)));
     }
     if ($this->fieldExists($table, $field)) {
       throw new SchemaObjectExistsException(t("Cannot add field @table.@field: field already exists.", array('@field' => $field, '@table' => $table)));
@@ -522,7 +522,7 @@ public function dropField($table, $field) {
 
   public function changeField($table, $field, $field_new, $spec, $keys_new = array()) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field doesn't exist.", array('@table' => $table, '@name' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field does not exist.", array('@table' => $table, '@name' => $field)));
     }
     if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
       throw new SchemaObjectExistsException(t("Cannot rename field @table.@name to @name_new: target field already exists.", array('@table' => $table, '@name' => $field, '@name_new' => $field_new)));
@@ -590,7 +590,7 @@ protected function mapKeyDefinition(array $key_definition, array $mapping) {
    */
   public function addIndex($table, $name, $fields, array $spec) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->indexExists($table, $name)) {
       throw new SchemaObjectExistsException(t("Cannot add index @name to table @table: index already exists.", array('@table' => $table, '@name' => $name)));
@@ -622,7 +622,7 @@ public function dropIndex($table, $name) {
 
   public function addUniqueKey($table, $name, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table does not exist.", array('@table' => $table, '@name' => $name)));
     }
     if ($this->indexExists($table, $name)) {
       throw new SchemaObjectExistsException(t("Cannot add unique key @name to table @table: unique key already exists.", array('@table' => $table, '@name' => $name)));
@@ -648,7 +648,7 @@ public function dropUniqueKey($table, $name) {
 
   public function addPrimaryKey($table, $fields) {
     if (!$this->tableExists($table)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table doesn't exist.", array('@table' => $table)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table does not exist.", array('@table' => $table)));
     }
 
     $old_schema = $this->introspectSchema($table);
@@ -677,7 +677,7 @@ public function dropPrimaryKey($table) {
 
   public function fieldSetDefault($table, $field, $default) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $old_schema = $this->introspectSchema($table);
@@ -689,7 +689,7 @@ public function fieldSetDefault($table, $field, $default) {
 
   public function fieldSetNoDefault($table, $field) {
     if (!$this->fieldExists($table, $field)) {
-      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));
+      throw new SchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field does not exist.", array('@table' => $table, '@field' => $field)));
     }
 
     $old_schema = $this->introspectSchema($table);
diff --git a/core/lib/Drupal/Core/Database/Install/Tasks.php b/core/lib/Drupal/Core/Database/Install/Tasks.php
index 9879998..f27e6a1 100644
--- a/core/lib/Drupal/Core/Database/Install/Tasks.php
+++ b/core/lib/Drupal/Core/Database/Install/Tasks.php
@@ -148,7 +148,7 @@ public function runTasks() {
           }
         }
         else {
-          $this->fail(t("Failed to run all tasks against the database server. The task %task wasn't found.", array('%task' => $task['function'])));
+          $this->fail(t("Failed to run all tasks against the database server. The task %task was not found.", array('%task' => $task['function'])));
         }
       }
     }
diff --git a/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php b/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
index be358b8..2589ca2 100644
--- a/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
+++ b/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
@@ -223,7 +223,7 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
 
     $form['auto_create'] = array(
       '#type' => 'checkbox',
-      '#title' => $this->t("Create referenced entities if they don't already exist"),
+      '#title' => $this->t("Create referenced entities if they do not already exist"),
       '#default_value' => $selection_handler_settings['auto_create'],
       '#weight' => -2,
     );
diff --git a/core/modules/aggregator/tests/modules/aggregator_test/aggregator_test_rss091.xml b/core/modules/aggregator/tests/modules/aggregator_test/aggregator_test_rss091.xml
index 84099fa..686f919 100644
--- a/core/modules/aggregator/tests/modules/aggregator_test/aggregator_test_rss091.xml
+++ b/core/modules/aggregator/tests/modules/aggregator_test/aggregator_test_rss091.xml
@@ -22,7 +22,7 @@
       <description>First example feed item description.</description>
     </item>
     <item>
-      <title>Second example feed item title. This title is extremely long so that it exceeds the 255 character limit for titles in feed item storage. In fact it's so long that this sentence isn't long enough so I'm rambling a bit to make it longer, nearly there now. Ah now it's long enough so I'll shut up.</title>
+      <title>Second example feed item title. This title is extremely long so that it exceeds the 255 character limit for titles in feed item storage. In fact it is so long that this sentence isn't long enough so I am rambling a bit to make it longer, nearly there now. Ah now it's long enough so I will shut up.</title>
       <link>http://example.com/example-turns-two</link>
       <description>Second example feed item description.</description>
     </item>
diff --git a/core/modules/block_content/tests/src/Kernel/Migrate/d7/MigrateCustomBlockTest.php b/core/modules/block_content/tests/src/Kernel/Migrate/d7/MigrateCustomBlockTest.php
index 824bad1..5e52713 100644
--- a/core/modules/block_content/tests/src/Kernel/Migrate/d7/MigrateCustomBlockTest.php
+++ b/core/modules/block_content/tests/src/Kernel/Migrate/d7/MigrateCustomBlockTest.php
@@ -49,7 +49,7 @@ public function testCustomBlockMigration() {
     /** @var \Drupal\block_content\BlockContentInterface $block */
     $this->assertIdentical('Limerick', $block->label());
 
-    $expected_body = "A fellow jumped off a high wall\r\nAnd had a most terrible fall\r\nHe went back to bed\r\nWith a bump on his head\r\nThat's why you don't jump off a wall";
+    $expected_body = "A fellow jumped off a high wall\r\nAnd had a most terrible fall\r\nHe went back to bed\r\nWith a bump on his head\r\nThat's why you do not jump off a wall";
     $this->assertIdentical($expected_body, $block->body->value);
     $this->assertIdentical('filtered_html', $block->body->format);
   }
diff --git a/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d7/BlockCustomTest.php b/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d7/BlockCustomTest.php
index 8da8730..18544ee 100644
--- a/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d7/BlockCustomTest.php
+++ b/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d7/BlockCustomTest.php
@@ -28,7 +28,7 @@ class BlockCustomTest extends MigrateSqlSourceTestCase {
   protected $expectedResults = array(
     array(
       'bid' => '1',
-      'body' => "I don't feel creative enough to write anything clever here.",
+      'body' => "I do not feel creative enough to write anything clever here.",
       'info' => 'Meh',
       'format' => 'filtered_html',
     ),
diff --git a/core/modules/book/src/Tests/BookBreadcrumbTest.php b/core/modules/book/src/Tests/BookBreadcrumbTest.php
index 7080a27..fe5bf57 100644
--- a/core/modules/book/src/Tests/BookBreadcrumbTest.php
+++ b/core/modules/book/src/Tests/BookBreadcrumbTest.php
@@ -181,7 +181,7 @@ public function testBreadcrumbAccessUpdates() {
     $nodes = $this->createBreadcrumbBook();
     $this->drupalLogin($this->bookAuthor);
     $edit = [
-      'title[0][value]' => "you can't see me",
+      'title[0][value]' => "you cannot see me",
     ];
     $this->drupalPostForm($nodes[3]->toUrl('edit-form'), $edit, 'Save');
     $this->drupalGet($nodes[4]->toUrl());
diff --git a/core/modules/book/tests/modules/book_breadcrumb_test/book_breadcrumb_test.module b/core/modules/book/tests/modules/book_breadcrumb_test/book_breadcrumb_test.module
index 526da71..99d59bd 100644
--- a/core/modules/book/tests/modules/book_breadcrumb_test/book_breadcrumb_test.module
+++ b/core/modules/book/tests/modules/book_breadcrumb_test/book_breadcrumb_test.module
@@ -15,7 +15,7 @@
  */
 function book_breadcrumb_test_node_access(NodeInterface $node, $operation, AccountInterface $account) {
   $config = \Drupal::config('book_breadcrumb_test.settings');
-  if ($config->get('hide') && $node->getTitle() == "you can't see me" && $operation == 'view') {
+  if ($config->get('hide') && $node->getTitle() == "you cannot see me" && $operation == 'view') {
     $access = new AccessResultForbidden();
   }
   else {
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
index 4511631..76f2d6b 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
@@ -77,7 +77,7 @@ public function testLinkApprove() {
 
     // Check if I can see the comment approve link on an approved comment.
     $approve_comment = $view->style_plugin->getField(1, 'approve_comment');
-    $this->assertFalse((string) $approve_comment, "Didn't find a comment approve link for an already approved comment.");
+    $this->assertFalse((string) $approve_comment, "Did not find a comment approve link for an already approved comment.");
 
     // Check if I can see the comment approve link on an approved comment as an
     // anonymous user.
@@ -89,7 +89,7 @@ public function testLinkApprove() {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'approve_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't approve the comment as an anonymous user.");
+    $this->assertFalse((string) $replyto_comment, "I cannot approve the comment as an anonymous user.");
   }
 
   /**
@@ -152,7 +152,7 @@ public function testLinkReply() {
 
     // Check if I can see the reply link on an unapproved comment.
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't reply to an unapproved comment.");
+    $this->assertFalse((string) $replyto_comment, "I cannot reply to an unapproved comment.");
 
     // Approve the comment.
     $comment->setPublished(CommentInterface::PUBLISHED);
@@ -175,6 +175,6 @@ public function testLinkReply() {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "Didn't find the comment reply link as an anonymous user.");
+    $this->assertFalse((string) $replyto_comment, "Did not find the comment reply link as an anonymous user.");
   }
 }
diff --git a/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php b/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php
index 26edb8e..98b0e1b 100644
--- a/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php
+++ b/core/modules/comment/tests/src/Unit/CommentLinkBuilderTest.php
@@ -85,7 +85,7 @@ protected function setUp() {
       ));
     $this->commentManager->expects($this->any())
       ->method('forbiddenMessage')
-      ->willReturn("Can't let you do that Dave.");
+      ->willReturn("cannot let you do that Dave.");
     $this->stringTranslation->expects($this->any())
       ->method('formatPlural')
       ->willReturnArgument(1);
@@ -244,7 +244,7 @@ public function getLinkCombinations() {
           elseif ($combination['is_anonymous']) {
             // Anonymous users get the forbidden message if the can't post
             // comments.
-            $expected['comment-forbidden'] = "Can't let you do that Dave.";
+            $expected['comment-forbidden'] = "cannot let you do that Dave.";
           }
         }
       }
diff --git a/core/modules/contact/contact.module b/core/modules/contact/contact.module
index 7cba6b1..3d795f6 100644
--- a/core/modules/contact/contact.module
+++ b/core/modules/contact/contact.module
@@ -152,7 +152,7 @@ function contact_mail($key, &$message, $params) {
       $message['subject'] .= t('[@site-name] @subject', $variables, $options);
       $message['body'][] = t('Hello @recipient-name,', $variables, $options);
       $message['body'][] = t("@sender-name (@sender-url) has sent you a message via your contact form at @site-name.", $variables, $options);
-      $message['body'][] = t("If you don't want to receive such emails, you can change your settings at @recipient-edit-url.", $variables, $options);
+      $message['body'][] = t("If you do not want to receive such emails, you can change your settings at @recipient-edit-url.", $variables, $options);
       $build = entity_view($contact_message, 'mail');
       $message['body'][] = \Drupal::service('renderer')->renderPlain($build);
       break;
diff --git a/core/modules/file/src/Tests/FileManagedTestBase.php b/core/modules/file/src/Tests/FileManagedTestBase.php
index 04b33aa..1fc991a 100644
--- a/core/modules/file/src/Tests/FileManagedTestBase.php
+++ b/core/modules/file/src/Tests/FileManagedTestBase.php
@@ -194,7 +194,7 @@ function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
     $filepath = $scheme . '://' . $filepath;
 
     if (!isset($contents)) {
-      $contents = "file_put_contents() doesn't seem to appreciate empty strings so let's put in some data.";
+      $contents = "file_put_contents() does not seem to appreciate empty strings so let's put in some data.";
     }
 
     file_put_contents($filepath, $contents);
diff --git a/core/modules/file/src/Tests/FileManagedUnitTestBase.php b/core/modules/file/src/Tests/FileManagedUnitTestBase.php
index 62ee4c2..65dc3dc 100644
--- a/core/modules/file/src/Tests/FileManagedUnitTestBase.php
+++ b/core/modules/file/src/Tests/FileManagedUnitTestBase.php
@@ -207,7 +207,7 @@ function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
     $filepath = $scheme . '://' . $filepath;
 
     if (!isset($contents)) {
-      $contents = "file_put_contents() doesn't seem to appreciate empty strings so let's put in some data.";
+      $contents = "file_put_contents() does not seem to appreciate empty strings so let's put in some data.";
     }
 
     file_put_contents($filepath, $contents);
diff --git a/core/modules/file/src/Tests/LoadTest.php b/core/modules/file/src/Tests/LoadTest.php
index 7a0fde9..6398c93 100644
--- a/core/modules/file/src/Tests/LoadTest.php
+++ b/core/modules/file/src/Tests/LoadTest.php
@@ -28,7 +28,7 @@ function testLoadMissingFid() {
    */
   function testLoadMissingFilepath() {
     $files = entity_load_multiple_by_properties('file', array('uri' => 'foobar://misc/druplicon.png'));
-    $this->assertFalse(reset($files), "Try to load a file that doesn't exist in the database fails.");
+    $this->assertFalse(reset($files), "Try to load a file that does not exist in the database fails.");
     $this->assertFileHooksCalled(array());
   }
 
diff --git a/core/modules/file/src/Tests/SaveTest.php b/core/modules/file/src/Tests/SaveTest.php
index ecd7d60..9ee6f1d 100644
--- a/core/modules/file/src/Tests/SaveTest.php
+++ b/core/modules/file/src/Tests/SaveTest.php
@@ -49,7 +49,7 @@ function testFileSave() {
     $this->assertFileHooksCalled(array('load', 'update'));
 
     $this->assertEqual($file->id(), $file->id(), 'The file ID of an existing file is not changed when updating the database.', 'File');
-    $this->assertTrue($file->getChangedTime() >= $file->getChangedTime(), "Timestamp didn't go backwards.", 'File');
+    $this->assertTrue($file->getChangedTime() >= $file->getChangedTime(), "Timestamp did not go backwards.", 'File');
     $loaded_file = File::load($file->id());
     $this->assertNotNull($loaded_file, 'Record still exists in the database.', 'File');
     $this->assertEqual($loaded_file->isPermanent(), $file->isPermanent(), 'Status was saved correctly.');
diff --git a/core/modules/filter/tests/filter.url-input.txt b/core/modules/filter/tests/filter.url-input.txt
index 92289dc..bf43f96 100644
--- a/core/modules/filter/tests/filter.url-input.txt
+++ b/core/modules/filter/tests/filter.url-input.txt
@@ -14,7 +14,7 @@ http://test.com/?search=test
 http://test.com/?search=Test
 http://test.com/?search=tesT
 
-What about tags that don't exist <x>like x say www.test.com</x>? And what about tag <pooh>beginning www.test.com with p?</pooh>
+What about tags that do not exist <x>like x say www.test.com</x>? And what about tag <pooh>beginning www.test.com with p?</pooh>
 
 Test &lt;br/&gt;: This is just a www.test.com. paragraph <strong>with</strong> some http://www.test.com urls thrown in. *<br/> This is just a www.test.com paragraph *<br/> with some http://www.test.com urls thrown in. *<br/>This is just a www.test.com paragraph person@test.com with some http://www.test.com urls *img*<img/> thrown in. This is just a www.test.com paragraph with some http://www.test.com urls thrown in. This is just a www.test.com paragraph person@test.com with some http://www.test.com urls thrown in.
 
@@ -36,4 +36,4 @@ The old URL filter has problems with <a title="kind of link www.example.com with
  inside a comment containing newlines and 
 <em>html</em> tags.</p> -->
 
-This is the end!
\ No newline at end of file
+This is the end!
diff --git a/core/modules/filter/tests/filter.url-output.txt b/core/modules/filter/tests/filter.url-output.txt
index 814a4ed..03c6b01 100644
--- a/core/modules/filter/tests/filter.url-output.txt
+++ b/core/modules/filter/tests/filter.url-output.txt
@@ -14,7 +14,7 @@ This is just a <a href="http://www.test.com">www.test.com</a>. paragraph with <a
 <a href="http://test.com/?search=Test">http://test.com/?search=Test</a>
 <a href="http://test.com/?search=tesT">http://test.com/?search=tesT</a>
 
-What about tags that don't exist <x>like x say <a href="http://www.test.com">www.test.com</a></x>? And what about tag <pooh>beginning <a href="http://www.test.com">www.test.com</a> with p?</pooh>
+What about tags that do not exist <x>like x say <a href="http://www.test.com">www.test.com</a></x>? And what about tag <pooh>beginning <a href="http://www.test.com">www.test.com</a> with p?</pooh>
 
 Test &lt;br/&gt;: This is just a <a href="http://www.test.com">www.test.com</a>. paragraph <strong>with</strong> some <a href="http://www.test.com">http://www.test.com</a> urls thrown in. *<br/> This is just a <a href="http://www.test.com">www.test.com</a> paragraph *<br/> with some <a href="http://www.test.com">http://www.test.com</a> urls thrown in. *<br/>This is just a <a href="http://www.test.com">www.test.com</a> paragraph <a href="mailto:person@test.com">person@test.com</a> with some <a href="http://www.test.com">http://www.test.com</a> urls *img*<img/> thrown in. This is just a <a href="http://www.test.com">www.test.com</a> paragraph with some <a href="http://www.test.com">http://www.test.com</a> urls thrown in. This is just a <a href="http://www.test.com">www.test.com</a> paragraph <a href="mailto:person@test.com">person@test.com</a> with some <a href="http://www.test.com">http://www.test.com</a> urls thrown in.
 
@@ -36,4 +36,4 @@ The old URL filter has problems with <a title="kind of link www.example.com with
  inside a comment containing newlines and 
 <em>html</em> tags.</p> -->
 
-This is the end!
\ No newline at end of file
+This is the end!
diff --git a/core/modules/image/image.install b/core/modules/image/image.install
index fd14d03..06a7878 100644
--- a/core/modules/image/image.install
+++ b/core/modules/image/image.install
@@ -53,7 +53,7 @@ function image_requirements($phase) {
       'image.toolkit' => array(
         'title' => t('Image toolkit'),
         'value' => t('None'),
-        'description' => t("No image toolkit is configured on the site. Check PHP installed extensions or add a contributed toolkit that doesn't require a PHP extension. Make sure that at least one valid image toolkit is enabled."),
+        'description' => t("No image toolkit is configured on the site. Check PHP installed extensions or add a contributed toolkit that does not require a PHP extension. Make sure that at least one valid image toolkit is enabled."),
         'severity' => REQUIREMENT_ERROR,
       ),
     );
diff --git a/core/modules/locale/src/Form/LocaleSettingsForm.php b/core/modules/locale/src/Form/LocaleSettingsForm.php
index ed1b488..21f185d 100644
--- a/core/modules/locale/src/Form/LocaleSettingsForm.php
+++ b/core/modules/locale/src/Form/LocaleSettingsForm.php
@@ -78,7 +78,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#title' => $this->t('Import behavior'),
       '#default_value' => $default,
       '#options' => array(
-        LOCALE_TRANSLATION_OVERWRITE_NONE => $this->t("Don't overwrite existing translations."),
+        LOCALE_TRANSLATION_OVERWRITE_NONE => $this->t("Do not overwrite existing translations."),
         LOCALE_TRANSLATION_OVERWRITE_NON_CUSTOMIZED => $this->t('Only overwrite imported translations, customized translations are kept.'),
         LOCALE_TRANSLATION_OVERWRITE_ALL => $this->t('Overwrite existing translations.'),
       ),
diff --git a/core/modules/locale/src/Tests/LocaleTranslationUiTest.php b/core/modules/locale/src/Tests/LocaleTranslationUiTest.php
index a6999b8..361e67e 100644
--- a/core/modules/locale/src/Tests/LocaleTranslationUiTest.php
+++ b/core/modules/locale/src/Tests/LocaleTranslationUiTest.php
@@ -428,7 +428,7 @@ public function testStringSearch() {
       'translation' => 'untranslated',
     );
     $this->drupalPostForm('admin/config/regional/translate', $search, t('Filter'));
-    $this->assertText(t('No strings available.'), "Search didn't find the source string.");
+    $this->assertText(t('No strings available.'), "Search did not find the source string.");
 
     // Ensure translated string doesn't appear if searching on 'only
     // untranslated strings'.
@@ -438,7 +438,7 @@ public function testStringSearch() {
       'translation' => 'untranslated',
     );
     $this->drupalPostForm('admin/config/regional/translate', $search, t('Filter'));
-    $this->assertText(t('No strings available.'), "Search didn't find the translation.");
+    $this->assertText(t('No strings available.'), "Search did not find the translation.");
 
     // Ensure translated string does appear if searching on the custom language.
     $search = array(
@@ -456,7 +456,7 @@ public function testStringSearch() {
       'translation' => 'all',
     );
     $this->drupalPostForm('admin/config/regional/translate', $search, t('Filter'));
-    $this->assertText(t('No strings available.'), "Search didn't find the translation.");
+    $this->assertText(t('No strings available.'), "Search did not find the translation.");
 
     // Search for a string that isn't in the system.
     $unavailable_string = $this->randomMachineName(16);
@@ -466,7 +466,7 @@ public function testStringSearch() {
       'translation' => 'all',
     );
     $this->drupalPostForm('admin/config/regional/translate', $search, t('Filter'));
-    $this->assertText(t('No strings available.'), "Search didn't find the invalid string.");
+    $this->assertText(t('No strings available.'), "Search did not find the invalid string.");
   }
 
   /**
diff --git a/core/modules/migrate/src/Row.php b/core/modules/migrate/src/Row.php
index 4e788af..ca33104 100644
--- a/core/modules/migrate/src/Row.php
+++ b/core/modules/migrate/src/Row.php
@@ -170,7 +170,7 @@ public function getSource() {
    */
   public function setSourceProperty($property, $data) {
     if ($this->frozen) {
-      throw new \Exception("The source is frozen and can't be changed any more");
+      throw new \Exception("The source is frozen and cannot be changed any more");
     }
     else {
       NestedArray::setValue($this->source, explode(static::PROPERTY_SEPARATOR, $property), $data, TRUE);
diff --git a/core/modules/migrate_drupal/tests/fixtures/drupal6.php b/core/modules/migrate_drupal/tests/fixtures/drupal6.php
index 1ca67a5..7ba5b5b 100644
--- a/core/modules/migrate_drupal/tests/fixtures/drupal6.php
+++ b/core/modules/migrate_drupal/tests/fixtures/drupal6.php
@@ -12385,7 +12385,7 @@
   'lid' => '355',
   'location' => 'modules/nodereference/nodereference.module:217',
   'textgroup' => 'default',
-  'source' => "%name: this post can't be referenced.",
+  'source' => "%name: this post cannot be referenced.",
   'version' => 'none',
 ))
 ->values(array(
@@ -17621,7 +17621,7 @@
   'lid' => '1104',
   'location' => '/?q=fr/admin/user/roles',
   'textgroup' => 'default',
-  'source' => "<p>Roles allow you to fine tune the security and administration of Drupal. A role defines a group of users that have certain privileges as defined in <a href=\"@permissions\">user permissions</a>. Examples of roles include: anonymous user, authenticated user, moderator, administrator and so on. In this area you will define the <em>role names</em> of the various roles. To delete a role choose \"edit\".</p><p>By default, Drupal comes with two user roles:</p>\n      <ul>\n      <li>Anonymous user: this role is used for users that don't have a user account or that are not authenticated.</li>\n      <li>Authenticated user: this role is automatically granted to all logged in users.</li>\n      </ul>",
+  'source' => "<p>Roles allow you to fine tune the security and administration of Drupal. A role defines a group of users that have certain privileges as defined in <a href=\"@permissions\">user permissions</a>. Examples of roles include: anonymous user, authenticated user, moderator, administrator and so on. In this area you will define the <em>role names</em> of the various roles. To delete a role choose \"edit\".</p><p>By default, Drupal comes with two user roles:</p>\n      <ul>\n      <li>Anonymous user: this role is used for users that do not have a user account or that are not authenticated.</li>\n      <li>Authenticated user: this role is automatically granted to all logged in users.</li>\n      </ul>",
   'version' => '6.38-dev',
 ))
 ->values(array(
diff --git a/core/modules/migrate_drupal/tests/fixtures/drupal7.php b/core/modules/migrate_drupal/tests/fixtures/drupal7.php
index fb307f0..11aad83 100644
--- a/core/modules/migrate_drupal/tests/fixtures/drupal7.php
+++ b/core/modules/migrate_drupal/tests/fixtures/drupal7.php
@@ -8345,7 +8345,7 @@
   'lid' => '18',
   'location' => 'modules/node/content_types.js',
   'textgroup' => 'default',
-  'source' => "Don't display post information",
+  'source' => "Do not display post information",
   'context' => '',
   'version' => 'none',
 ))
diff --git a/core/modules/node/content_types.js b/core/modules/node/content_types.js
index eed93f0..5e07d50 100644
--- a/core/modules/node/content_types.js
+++ b/core/modules/node/content_types.js
@@ -52,7 +52,7 @@
           vals.push(Drupal.checkPlain($(this).text()));
         });
         if (!$editContext.find('#edit-display-submitted').is(':checked')) {
-          vals.unshift(Drupal.t("Don't display post information"));
+          vals.unshift(Drupal.t("Do not display post information"));
         }
         return vals.join(', ');
       });
diff --git a/core/modules/node/src/Tests/NodeFormSaveChangedTimeTest.php b/core/modules/node/src/Tests/NodeFormSaveChangedTimeTest.php
index 285a743..64fa572 100644
--- a/core/modules/node/src/Tests/NodeFormSaveChangedTimeTest.php
+++ b/core/modules/node/src/Tests/NodeFormSaveChangedTimeTest.php
@@ -62,7 +62,7 @@ public function testChangedTimeAfterSaveWithoutChanges() {
 
     $node->save();
     $node = entity_load('node', 1, TRUE);
-    $this->assertEqual($changed_timestamp, $node->getChangedTime(), "The entity's changed time wasn't updated after API save without changes.");
+    $this->assertEqual($changed_timestamp, $node->getChangedTime(), "The entity's changed time was not updated after API save without changes.");
 
     // Ensure different save timestamps.
     sleep(1);
diff --git a/core/modules/search/src/Form/ReindexConfirm.php b/core/modules/search/src/Form/ReindexConfirm.php
index 4661918..f621a8d 100644
--- a/core/modules/search/src/Form/ReindexConfirm.php
+++ b/core/modules/search/src/Form/ReindexConfirm.php
@@ -34,7 +34,7 @@ public function getQuestion() {
    * {@inheritdoc}
    */
   public function getDescription() {
-    return $this->t("This will re-index content in the search indexes of all active search pages. Searching will continue to work, but new content won't be indexed until all existing content has been re-indexed. This action cannot be undone.");
+    return $this->t("This will re-index content in the search indexes of all active search pages. Searching will continue to work, but new content would not be indexed until all existing content has been re-indexed. This action cannot be undone.");
   }
 
   /**
diff --git a/core/modules/search/src/SearchPageListBuilder.php b/core/modules/search/src/SearchPageListBuilder.php
index ded4461..04b29fb 100644
--- a/core/modules/search/src/SearchPageListBuilder.php
+++ b/core/modules/search/src/SearchPageListBuilder.php
@@ -220,7 +220,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#open' => TRUE,
     );
     $form['indexing_settings']['info'] = array(
-      '#markup' => $this->t("<p>Search pages that use an index may use the default index provided by the Search module, or they may use a different indexing mechanism. These settings are for the default index. <em>Changing these settings will cause the default search index to be rebuilt to reflect the new settings. Searching will continue to work, based on the existing index, but new content won't be indexed until all existing content has been re-indexed.</em></p><p><em>The default settings should be appropriate for the majority of sites.</em></p>")
+      '#markup' => $this->t("<p>Search pages that use an index may use the default index provided by the Search module, or they may use a different indexing mechanism. These settings are for the default index. <em>Changing these settings will cause the default search index to be rebuilt to reflect the new settings. Searching will continue to work, based on the existing index, but new content would not be indexed until all existing content has been re-indexed.</em></p><p><em>The default settings should be appropriate for the majority of sites.</em></p>")
     );
     $form['indexing_settings']['minimum_word_size'] = array(
       '#type' => 'number',
diff --git a/core/modules/search/src/Tests/SearchAdvancedSearchFormTest.php b/core/modules/search/src/Tests/SearchAdvancedSearchFormTest.php
index 3650a93..cd85d0c 100644
--- a/core/modules/search/src/Tests/SearchAdvancedSearchFormTest.php
+++ b/core/modules/search/src/Tests/SearchAdvancedSearchFormTest.php
@@ -46,7 +46,7 @@ function testNodeType() {
     // Verify some properties of the node that was created.
     $this->assertTrue($this->node->getType() == 'page', 'Node type is Basic page.');
     $dummy_title = 'Lorem ipsum';
-    $this->assertNotEqual($dummy_title, $this->node->label(), "Dummy title doesn't equal node title.");
+    $this->assertNotEqual($dummy_title, $this->node->label(), "Dummy title does not equal node title.");
 
     // Search for the dummy title with a GET query.
     $this->drupalGet('search/node', array('query' => array('keys' => $dummy_title)));
diff --git a/core/modules/simpletest/src/BrowserTestBase.php b/core/modules/simpletest/src/BrowserTestBase.php
index dc933ac..1669a30 100644
--- a/core/modules/simpletest/src/BrowserTestBase.php
+++ b/core/modules/simpletest/src/BrowserTestBase.php
@@ -265,7 +265,7 @@ protected function getDefaultDriverInstance() {
         $this->minkDefaultDriverClass = $minkDriverClass;
       }
       else {
-        throw new \InvalidArgumentException("Can't instantiate provided $minkDriverClass class by environment as default driver class.");
+        throw new \InvalidArgumentException("Cannot instantiate provided $minkDriverClass class by environment as default driver class.");
       }
     }
 
diff --git a/core/modules/system/src/Controller/DbUpdateController.php b/core/modules/system/src/Controller/DbUpdateController.php
index 0239a41..cfcd02d 100644
--- a/core/modules/system/src/Controller/DbUpdateController.php
+++ b/core/modules/system/src/Controller/DbUpdateController.php
@@ -426,7 +426,7 @@ protected function results(Request $request) {
     }
 
     if (Settings::get('update_free_access')) {
-      $message .= '<p>' . $this->t("<strong>Reminder: don't forget to set the <code>\$settings['update_free_access']</code> value in your <code>settings.php</code> file back to <code>FALSE</code>.</strong>")  . '</p>';
+      $message .= '<p>' . $this->t("<strong>Reminder: do not forget to set the <code>\$settings['update_free_access']</code> value in your <code>settings.php</code> file back to <code>FALSE</code>.</strong>")  . '</p>';
     }
 
     $build['message'] = array(
diff --git a/core/modules/system/src/Form/ThemeSettingsForm.php b/core/modules/system/src/Form/ThemeSettingsForm.php
index 82ad415..be540b6 100644
--- a/core/modules/system/src/Form/ThemeSettingsForm.php
+++ b/core/modules/system/src/Form/ThemeSettingsForm.php
@@ -208,7 +208,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $theme =
         '#type' => 'file',
         '#title' => t('Upload logo image'),
         '#maxlength' => 40,
-        '#description' => t("If you don't have direct file access to the server, use this field to upload your logo.")
+        '#description' => t("If you do not have direct file access to the server, use this field to upload your logo.")
       );
     }
 
@@ -248,7 +248,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $theme =
       $form['favicon']['settings']['favicon_upload'] = array(
         '#type' => 'file',
         '#title' => t('Upload icon image'),
-        '#description' => t("If you don't have direct file access to the server, use this field to upload your shortcut icon.")
+        '#description' => t("If you do not have direct file access to the server, use this field to upload your shortcut icon.")
       );
     }
 
diff --git a/core/modules/system/src/Tests/File/FileSaveHtaccessLoggingTest.php b/core/modules/system/src/Tests/File/FileSaveHtaccessLoggingTest.php
index 544e8b1..e75b201 100644
--- a/core/modules/system/src/Tests/File/FileSaveHtaccessLoggingTest.php
+++ b/core/modules/system/src/Tests/File/FileSaveHtaccessLoggingTest.php
@@ -32,7 +32,7 @@ function testHtaccessSave() {
     $this->assertFalse(file_save_htaccess($private, TRUE));
     $this->drupalLogin($this->rootUser);
     $this->drupalGet('admin/reports/dblog');
-    $this->clickLink("Security warning: Couldn't write .htaccess file. Please…");
+    $this->clickLink("Security warning: Could not write .htaccess file. Please…");
 
     $lines = FileStorage::htaccessLines(TRUE);
     foreach (array_filter(explode("\n", $lines)) as $line) {
diff --git a/core/modules/system/src/Tests/File/FileTestBase.php b/core/modules/system/src/Tests/File/FileTestBase.php
index 93e998d..7d3d086 100644
--- a/core/modules/system/src/Tests/File/FileTestBase.php
+++ b/core/modules/system/src/Tests/File/FileTestBase.php
@@ -162,7 +162,7 @@ function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
     $filepath = $scheme . '://' . $filepath;
 
     if (!isset($contents)) {
-      $contents = "file_put_contents() doesn't seem to appreciate empty strings so let's put in some data.";
+      $contents = "file_put_contents() doesnot seem to appreciate empty strings so let's put in some data.";
     }
 
     file_put_contents($filepath, $contents);
diff --git a/core/modules/system/src/Tests/File/ScanDirectoryTest.php b/core/modules/system/src/Tests/File/ScanDirectoryTest.php
index 4b067f0..3616c31 100644
--- a/core/modules/system/src/Tests/File/ScanDirectoryTest.php
+++ b/core/modules/system/src/Tests/File/ScanDirectoryTest.php
@@ -128,7 +128,7 @@ function testOptionKey() {
    */
   function testOptionRecurse() {
     $files = file_scan_directory($this->path . '/..', '/^javascript-/', array('recurse' => FALSE));
-    $this->assertTrue(empty($files), "Without recursion couldn't find javascript files.");
+    $this->assertTrue(empty($files), "Without recursion could not find javascript files.");
 
     $files = file_scan_directory($this->path . '/..', '/^javascript-/', array('recurse' => TRUE));
     $this->assertEqual(2, count($files), 'With recursion we found the expected javascript files.');
diff --git a/core/modules/system/src/Tests/File/UnmanagedCopyTest.php b/core/modules/system/src/Tests/File/UnmanagedCopyTest.php
index 22a0615..55681c5 100644
--- a/core/modules/system/src/Tests/File/UnmanagedCopyTest.php
+++ b/core/modules/system/src/Tests/File/UnmanagedCopyTest.php
@@ -52,7 +52,7 @@ function testNormal() {
   function testNonExistent() {
     // Copy non-existent file
     $desired_filepath = $this->randomMachineName();
-    $this->assertFalse(file_exists($desired_filepath), "Randomly named file doesn't exists.");
+    $this->assertFalse(file_exists($desired_filepath), "Randomly named file does not exists.");
     $new_filepath = file_unmanaged_copy($desired_filepath, $this->randomMachineName());
     $this->assertFalse($new_filepath, 'Copying a missing file fails.');
   }
diff --git a/core/modules/system/src/Tests/Routing/RouterPermissionTest.php b/core/modules/system/src/Tests/Routing/RouterPermissionTest.php
index b3d5706..4862d67 100644
--- a/core/modules/system/src/Tests/Routing/RouterPermissionTest.php
+++ b/core/modules/system/src/Tests/Routing/RouterPermissionTest.php
@@ -29,7 +29,7 @@ class RouterPermissionTest extends WebTestBase {
   public function testPermissionAccess() {
     $path = 'router_test/test7';
     $this->drupalGet($path);
-    $this->assertResponse(403, "Access denied for a route where we don't have a permission");
+    $this->assertResponse(403, "Access denied for a route where we do not have a permission");
 
     $this->drupalGet('router_test/test8');
     $this->assertResponse(403, 'Access denied by default if no access specified');
diff --git a/core/modules/system/src/Tests/Theme/StableThemeTest.php b/core/modules/system/src/Tests/Theme/StableThemeTest.php
index 0df5c71..1cfd07b 100644
--- a/core/modules/system/src/Tests/Theme/StableThemeTest.php
+++ b/core/modules/system/src/Tests/Theme/StableThemeTest.php
@@ -57,7 +57,7 @@ public function testStableIsDefault() {
     /** @var \Drupal\Core\Theme\ActiveTheme $base_theme */
     $base_themes = $theme->getBaseThemes();
     $base_theme = reset($base_themes);
-    $this->assertTrue($base_theme->getName() == 'stable', "Stable theme is the base theme if a theme hasn't decided to opt out.");
+    $this->assertTrue($base_theme->getName() == 'stable', "Stable theme is the base theme if a theme has not decided to opt out.");
   }
 
   /**
diff --git a/core/modules/user/src/PrivateTempStore.php b/core/modules/user/src/PrivateTempStore.php
index d85c21d..027c32a 100644
--- a/core/modules/user/src/PrivateTempStore.php
+++ b/core/modules/user/src/PrivateTempStore.php
@@ -123,7 +123,7 @@ public function set($key, $value) {
     if (!$this->lockBackend->acquire($key)) {
       $this->lockBackend->wait($key);
       if (!$this->lockBackend->acquire($key)) {
-        throw new TempStoreException("Couldn't acquire lock to update item '$key' in '{$this->storage->getCollectionName()}' temporary storage.");
+        throw new TempStoreException("Could not acquire lock to update item '$key' in '{$this->storage->getCollectionName()}' temporary storage.");
       }
     }
 
@@ -178,7 +178,7 @@ public function delete($key) {
     if (!$this->lockBackend->acquire($key)) {
       $this->lockBackend->wait($key);
       if (!$this->lockBackend->acquire($key)) {
-        throw new TempStoreException("Couldn't acquire lock to delete item '$key' from '{$this->storage->getCollectionName()}' temporary storage.");
+        throw new TempStoreException("Could not acquire lock to delete item '$key' from '{$this->storage->getCollectionName()}' temporary storage.");
       }
     }
     $this->storage->delete($key);
diff --git a/core/modules/user/src/SharedTempStore.php b/core/modules/user/src/SharedTempStore.php
index 07e4756..89ea72f 100644
--- a/core/modules/user/src/SharedTempStore.php
+++ b/core/modules/user/src/SharedTempStore.php
@@ -195,7 +195,7 @@ public function set($key, $value) {
     if (!$this->lockBackend->acquire($key)) {
       $this->lockBackend->wait($key);
       if (!$this->lockBackend->acquire($key)) {
-        throw new TempStoreException("Couldn't acquire lock to update item '$key' in '{$this->storage->getCollectionName()}' temporary storage.");
+        throw new TempStoreException("Could not acquire lock to update item '$key' in '{$this->storage->getCollectionName()}' temporary storage.");
       }
     }
 
@@ -238,7 +238,7 @@ public function delete($key) {
     if (!$this->lockBackend->acquire($key)) {
       $this->lockBackend->wait($key);
       if (!$this->lockBackend->acquire($key)) {
-        throw new TempStoreException("Couldn't acquire lock to delete item '$key' from {$this->storage->getCollectionName()} temporary storage.");
+        throw new TempStoreException("Could not acquire lock to delete item '$key' from {$this->storage->getCollectionName()} temporary storage.");
       }
     }
     $this->storage->delete($key);
diff --git a/core/modules/views/src/ManyToOneHelper.php b/core/modules/views/src/ManyToOneHelper.php
index 71a49e8..46e65d7 100644
--- a/core/modules/views/src/ManyToOneHelper.php
+++ b/core/modules/views/src/ManyToOneHelper.php
@@ -38,7 +38,7 @@ public function buildOptionsForm(&$form, FormStateInterface $form_state) {
     $form['reduce_duplicates'] = array(
       '#type' => 'checkbox',
       '#title' => t('Reduce duplicates'),
-      '#description' => t("This filter can cause items that have more than one of the selected options to appear as duplicate results. If this filter causes duplicate results to occur, this checkbox can reduce those duplicates; however, the more terms it has to search for, the less performant the query will be, so use this with caution. Shouldn't be set on single-value fields, as it may cause values to disappear from display, if used on an incompatible field."),
+      '#description' => t("This filter can cause items that have more than one of the selected options to appear as duplicate results. If this filter causes duplicate results to occur, this checkbox can reduce those duplicates; however, the more terms it has to search for, the less performant the query will be, so use this with caution. Should not be set on single-value fields, as it may cause values to disappear from display, if used on an incompatible field."),
       '#default_value' => !empty($this->handler->options['reduce_duplicates']),
       '#weight' => 4,
     );
diff --git a/core/modules/views/src/Plugin/views/filter/Combine.php b/core/modules/views/src/Plugin/views/filter/Combine.php
index a0889c9..7ae3e40 100644
--- a/core/modules/views/src/Plugin/views/filter/Combine.php
+++ b/core/modules/views/src/Plugin/views/filter/Combine.php
@@ -48,7 +48,7 @@ public function buildOptionsForm(&$form, FormStateInterface $form_state) {
         $form['fields'] = array(
           '#type' => 'select',
           '#title' => $this->t('Choose fields to combine for filtering'),
-          '#description' => $this->t("This filter doesn't work for very special field handlers."),
+          '#description' => $this->t("This filter does not work for very special field handlers."),
           '#multiple' => TRUE,
           '#options' => $options,
           '#default_value' => $this->options['fields'],
diff --git a/core/modules/views/src/Tests/Handler/FieldWebTest.php b/core/modules/views/src/Tests/Handler/FieldWebTest.php
index 2d43a10..e0f1616 100644
--- a/core/modules/views/src/Tests/Handler/FieldWebTest.php
+++ b/core/modules/views/src/Tests/Handler/FieldWebTest.php
@@ -566,7 +566,7 @@ public function testTextRendering() {
       return $name_field->advancedRender($row);
     });
     $this->assertSubString($output, $trimmed_name, format_string('Make sure the trimmed output (@trimmed) appears in the rendered output (@output).', array('@trimmed' => $trimmed_name, '@output' => $output)));
-    $this->assertNotSubString($output, $row->views_test_data_name, format_string("Make sure the untrimmed value (@untrimmed) shouldn't appear in the rendered output (@output).", array('@untrimmed' => $row->views_test_data_name, '@output' => $output)));
+    $this->assertNotSubString($output, $row->views_test_data_name, format_string("Make sure the untrimmed value (@untrimmed) should not appear in the rendered output (@output).", array('@untrimmed' => $row->views_test_data_name, '@output' => $output)));
 
     $name_field->options['alter']['max_length'] = 9;
     $output = $renderer->executeInRenderContext(new RenderContext(), function () use ($name_field, $row) {
diff --git a/core/modules/views/src/Tests/Plugin/StyleTableTest.php b/core/modules/views/src/Tests/Plugin/StyleTableTest.php
index 30ea610..bea6257 100644
--- a/core/modules/views/src/Tests/Plugin/StyleTableTest.php
+++ b/core/modules/views/src/Tests/Plugin/StyleTableTest.php
@@ -201,7 +201,7 @@ public function testGrouping() {
     );
 
     // Ensure that we don't find the caption containing unsafe markup.
-    $this->assertNoRaw($unsafe_markup, "Didn't find caption containing unsafe markup.");
+    $this->assertNoRaw($unsafe_markup, "Did not find caption containing unsafe markup.");
 
     // Ensure that all expected captions are found.
     foreach ($expected_captions as $raw_caption) {
@@ -223,7 +223,7 @@ public function testGrouping() {
     );
 
     // Ensure that we don't find the caption containing unsafe markup.
-    $this->assertNoRaw($unsafe_markup, "Didn't find caption containing unsafe markup.");
+    $this->assertNoRaw($unsafe_markup, "Did not find caption containing unsafe markup.");
 
     // Ensure that all expected captions are found.
     foreach ($expected_captions as $raw_caption) {
diff --git a/core/modules/views/tests/src/Kernel/Handler/FieldKernelTest.php b/core/modules/views/tests/src/Kernel/Handler/FieldKernelTest.php
index c5bfb5d..3b44c2f 100644
--- a/core/modules/views/tests/src/Kernel/Handler/FieldKernelTest.php
+++ b/core/modules/views/tests/src/Kernel/Handler/FieldKernelTest.php
@@ -195,7 +195,7 @@ public function testArgumentTokens() {
     });
 
     $this->assertFalse(strpos((string) $output, 'views_test_data_test_pre_render_function executed') !== FALSE, 'Ensure that the pre_render function was not executed');
-    $this->assertEqual('%1 !1', (string) $output, "Ensure that old style placeholders aren't replaced");
+    $this->assertEqual('%1 !1', (string) $output, "Ensure that old style placeholders are not replaced");
 
     // This time use new style tokens but ensure that we still don't allow
     // arbitrary code execution.
diff --git a/core/modules/views/tests/src/Kernel/ViewExecutableTest.php b/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
index db50c39..e7ff751 100644
--- a/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
+++ b/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
@@ -410,7 +410,7 @@ public function testGetHandlers() {
     $view->getHandlers('field', 'page_2');
 
     // getHandlers() shouldn't change the active display.
-    $this->assertEqual('page_1', $view->current_display, "The display shouldn't change after getHandlers()");
+    $this->assertEqual('page_1', $view->current_display, "The display should not change after getHandlers()");
   }
 
   /**
diff --git a/core/modules/views_ui/src/Form/Ajax/ConfigHandler.php b/core/modules/views_ui/src/Form/Ajax/ConfigHandler.php
index d3fdd6a..e15e371 100644
--- a/core/modules/views_ui/src/Form/Ajax/ConfigHandler.php
+++ b/core/modules/views_ui/src/Form/Ajax/ConfigHandler.php
@@ -77,7 +77,7 @@ public function buildForm(array $form, FormStateInterface $form_state, Request $
     if ($item) {
       $handler = $executable->display_handler->getHandler($type, $id);
       if (empty($handler)) {
-        $form['markup'] = array('#markup' => $this->t("Error: handler for @table > @field doesn't exist!", array('@table' => $item['table'], '@field' => $item['field'])));
+        $form['markup'] = array('#markup' => $this->t("Error: handler for @table > @field does not exist!", array('@table' => $item['table'], '@field' => $item['field'])));
       }
       else {
         $types = ViewExecutable::getHandlerTypes();
diff --git a/core/modules/views_ui/src/Form/Ajax/ConfigHandlerExtra.php b/core/modules/views_ui/src/Form/Ajax/ConfigHandlerExtra.php
index a3917f0..119b1ca 100644
--- a/core/modules/views_ui/src/Form/Ajax/ConfigHandlerExtra.php
+++ b/core/modules/views_ui/src/Form/Ajax/ConfigHandlerExtra.php
@@ -73,7 +73,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     if ($item) {
       $handler = $executable->display_handler->getHandler($type, $id);
       if (empty($handler)) {
-        $form['markup'] = array('#markup' => $this->t("Error: handler for @table > @field doesn't exist!", array('@table' => $item['table'], '@field' => $item['field'])));
+        $form['markup'] = array('#markup' => $this->t("Error: handler for @table > @field does not exist!", array('@table' => $item['table'], '@field' => $item['field'])));
       }
       else {
         $handler->init($executable, $executable->display_handler, $item);
diff --git a/core/modules/views_ui/tests/src/Kernel/TagTest.php b/core/modules/views_ui/tests/src/Kernel/TagTest.php
index 54f34df..44d1687 100644
--- a/core/modules/views_ui/tests/src/Kernel/TagTest.php
+++ b/core/modules/views_ui/tests/src/Kernel/TagTest.php
@@ -71,7 +71,7 @@ public function testViewsUiAutocompleteTag() {
     $request->query->set('q', $this->randomMachineName());
     $result = $controller->autocompleteTag($request);
     $matches = (array) json_decode($result->getContent());
-    $this->assertEqual(count($matches), 0, "Make sure an invalid tag doesn't return anything.");
+    $this->assertEqual(count($matches), 0, "Make sure an invalid tag does not return anything.");
   }
 
 }