I have created a file theme taxonomy-tem by use module view.

// $Id: views-view.tpl.php,v 1.11 2008/12/02 18:35:50 merlinofchaos Exp $
/**
 * @file views-view.tpl.php
 * Main view template
 *
 * Variables available:
 * - $css_name: A css-safe version of the view name.
 * - $header: The view header
 * - $footer: The view footer
 * - $rows: The results of the view query, if any
 * - $empty: The empty text to display if the view is empty
 * - $pager: The pager next/prev links to display, if any
 * - $exposed: Exposed widget form/info to display
 * - $feed_icon: Feed icon to display, if any
 * - $more: A link to view more, if any
 * - $admin_links: A rendered list of administrative links
 * - $admin_links_raw: A list of administrative links suitable for theme('links')
 *
 * @ingroup views_templates
 */
print $css_name; view-id- print $name; view-display-id- print $display_id; view-dom-id- print $dom_id; ">
jhhhhhhhhhhhhhhhhhhhhhhh

if ($rows):

print $rows; // print node teaser . i want to insert a block when node teaser repeat three.

elseif ($empty):

print $empty;

endif;

heeeeeeeeeeeeeeeeeeeeeeeeee

if ($pager):
print $pager;
endif;

if ($attachment_after):

print $attachment_after;

endif;

if ($more):
print $more;
endif;

if ($footer):

endif;

// class view