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="开源项目计划" />
  </query-continue>
  <query>
    <pages>
      <page pageid="51" ns="0" title="Xmemcached 中文用户指南" touched="2016-07-28T12:31:01Z" lastrevid="412" counter="1855" length="34626" />
      <page pageid="21" ns="0" title="Xproject api设计" touched="2013-01-11T11:06:24Z" lastrevid="303" counter="81582" length="6831" />
      <page pageid="33" ns="0" title="外借的书籍" touched="2013-01-10T08:15:17Z" lastrevid="302" counter="4868" length="153" />
      <page pageid="48" ns="0" title="如何高效学习" touched="2016-07-24T12:21:47Z" lastrevid="393" counter="2713" length="1867" />
    </pages>
  </query>
</api>