页面代码问题

两个文件，A.php B.html
在A里面引用B，然后在IE浏览器里分别访问这两个文件，结果访问A看到的内容比访问B看到的内容上方要多出一行空白。
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A.php源代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题 1</title>
</head><body>
<?php include("template/B.html");?>
</body></html>
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B.html源代码：
<div id="footer" class="clearDiv">
<table width="100%" border="0" cellspacing="0" cellpadding="0" class="tblBorder" style="margin-top:10px;">
  <tr>
<td width="5" height="5" align="left" valign="top"><div class="tblTopLeftCorner"></div></td>
<td width="100%" height="21" rowspan="3" align="center" valign="middle" >
<script>document.write(copyrightyear)</script><strong> UniSoft, Inc</strong>. All rights reserved. <a href="trades.html" tppabs="http://www.adventnet.com/trades.html" target="_blank">Trades</a> |<a href="privacy.html" tppabs="http://www.adventnet.com/privacy.html" target="_blank"> Privacy Policy</a> |<a href="sitemap.html" tppabs="http://www.adventnet.com/sitemap.html" target="_blank"> Site Map</a> |<a href="contact.html" tppabs="http://www.uni-soft.cn/contact.html"> Contact Us</a> | <a href="careers.html" tppabs="http://www.adventnet.com/careers.html" target="_blank">Careers</a>  <!--a href="javascript:popUp('http://www.adventnet.com/feedback.html?referer='+document.URL,'ref','','instant',500,400,0);" class="topframelink">Tell Us</a--></td>
<td width="5" height="5" align="right" valign="top"><div class="tblTopRightCorner"></div></td>
   </tr>
<tr><td align="left" valign="top"></td><td align="left" valign="top"></td></tr>
  <tr><td width="5" height="5" align="left" valign="bottom"><div class="tblBotLeftCorner"></div></td>
  <td width="5" height="5" align="right" valign="bottom"><div class="tblBotRightCorner"></div></td>
  </tr>
</table>
</div>
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不知道是什么原因？请高手们指教！谢谢！