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="1.What-is-a-Spoken-Tutorial-Farsi.pdf" />
  </query-continue>
  <query>
    <pages>
      <page pageid="7663" ns="6" title="File:1.Command line arguments in C.pdf" />
      <page pageid="7341" ns="6" title="File:1.First C Program.pdf" />
      <page pageid="7000" ns="6" title="File:1.Getting Started with Ktouch.pdf" />
      <page pageid="8027" ns="6" title="File:1.Hello Ruby.pdf">
        <duplicatefiles>
          <df name="1.Hello_Ruby_Kashmiri.pdf" user="Wajahat" timestamp="2018-06-29T07:51:12Z" />
        </duplicatefiles>
      </page>
      <page pageid="12041" ns="6" title="File:1.Hello Ruby Kashmiri.pdf">
        <duplicatefiles>
          <df name="1.Hello_Ruby.pdf" user="Wajahat" timestamp="2018-06-29T07:48:10Z" />
        </duplicatefiles>
      </page>
      <page pageid="12878" ns="6" title="File:1.Installing VirtualBox in Windows OS.pdf" />
      <page pageid="7022" ns="6" title="File:1.Introduction-to-Geogebra.pdf" />
      <page pageid="3288" ns="6" title="File:1.Introduction.pdf" />
      <page pageid="8240" ns="6" title="File:1.Overview of Drupal.pdf" />
      <page pageid="8047" ns="6" title="File:1.Overview of Library Management System.pdf" />
    </pages>
  </query>
</api>