jquery 选择操作元素

<ul class="my-list">
   <li>
      <a href="http://jquery.com">jQuery website</a>
      <ul>
         <li><a href="#css1">CSS1</a></li>
         <li><a href="#css2">CSS2</a></li>
         <li><a href="#css3">CSS3</a></li>
         <li>Basic XPath</li>
      </ul>
   </li>
   <li>
      jQuery also supports
      <ul>
         <li>Custom selectors</li>
         <li>Form selectors</li>
      </ul>
   </li>