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>
    <allimages gaicontinue="Cholecalciferol.PNG" />
  </query-continue>
  <query>
    <pages>
      <page pageid="74" ns="6" title="文件:20种氨基酸.png" />
      <page pageid="166" ns="6" title="文件:22-Dihydroergocalciferol.png" />
      <page pageid="66" ns="6" title="文件:AFB1与其他毒物的LD50对比.png" />
      <page pageid="65" ns="6" title="文件:AFB1代谢.png" />
      <page pageid="67" ns="6" title="文件:AFB1对大鼠致癌性.png" />
      <page pageid="112" ns="6" title="文件:Amadori重排反应.PNG" />
      <page pageid="124" ns="6" title="文件:Amylose 3Dprojection.corrected.png" />
      <page pageid="108" ns="6" title="文件:Benzopyrene diol epoxide chemical structure.png" />
      <page pageid="170" ns="6" title="文件:Calcium regulation.png" />
      <page pageid="123" ns="6" title="文件:Cellulose-Ibeta-from-xtal-2002-3D-balls.png" />
    </pages>
  </query>
</api>