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>
    <exturlusage euoffset="10" />
  </query-continue>
  <query>
    <exturlusage>
      <eu pageid="4" ns="0" title="2015级工程管理硕士（MEM）入学导引课" url="http://www.mediawiki.org" />
      <eu pageid="322" ns="0" title="Group6" url="http://www.mediawiki.org" />
      <eu pageid="2376" ns="0" title="B组-清华地图及脚本汇报" url="http://www.mediawiki.org" />
      <eu pageid="9254" ns="0" title="测试功能页面" url="http://www.mediawiki.org" />
      <eu pageid="1" ns="0" title="首页" url="//www.mediawiki.org/wiki/Localisation#Translation_resources" />
      <eu pageid="1" ns="0" title="首页" url="//www.mediawiki.org/wiki/Manual:Configuration_settings" />
      <eu pageid="1" ns="0" title="首页" url="//www.mediawiki.org/wiki/Manual:FAQ/zh-hans" />
      <eu pageid="3616" ns="0" title="《超越学科的认知基础》2015秋顧學雍学习报告-第三周" url="http://www.mediawiki.org/wiki/Manual:Namespace" />
      <eu pageid="9886" ns="0" title="笔记" url="//www.mediawiki.org/wiki/Special:MyLanguage/Localisation#Translation_resources" />
      <eu pageid="9886" ns="0" title="笔记" url="//www.mediawiki.org/wiki/Special:MyLanguage/Manual:Combating_spam" />
    </exturlusage>
  </query>
</api>