index.html（xpath素材）

<bookstore>

    <title>新华书店</title>

    <book href="http://www.langlang2017.com/">
      <title lang="eng">Harry Potter</title>
      <price>29.99</price>
    </book>

    <book>
      <title lang="zh">Learning XML</title>
      <price>39.95</price>
    </book>

    <book>
      <title>python 大全</title>
      <price>99.95</price>
    </book>
    
</bookstore>