You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages gapcontinue="UCenter/数据库字典" />
  </query-continue>
  <query>
    <pages>
      <page pageid="840" ns="0" title="TCP/IP" contentmodel="wikitext" pagelanguage="zh-cn" touched="2008-06-07T04:18:48Z" lastrevid="2893" counter="1451" length="389" new="" />
      <page pageid="1294" ns="0" title="Tab选项卡" contentmodel="wikitext" pagelanguage="zh-cn" touched="2010-02-02T12:19:54Z" lastrevid="6587" counter="19624" length="2579" />
      <page pageid="1899" ns="0" title="The Event Flow" contentmodel="wikitext" pagelanguage="zh-cn" touched="2011-04-15T01:27:37Z" lastrevid="8203" counter="86887" length="11005" />
      <page pageid="1601" ns="0" title="UCenter" contentmodel="wikitext" pagelanguage="zh-cn" touched="2014-10-21T15:02:14Z" lastrevid="9872" counter="19044" length="814" />
    </pages>
  </query>
</api>