小编use*_*594的帖子

I have

   <div id="aa">
   <img src="." height="17" alt="example1" title="">
       <table>
            <tbody><tr>
              <th></th>
              <td></td>
       </tbody>
       </table>


   <img src="." height="17" alt="example2" title="">
       <table>
            <tbody><tr>
              <th></th>
              <td></td>
       </tbody>
       </table>


   <img src="." height="17" alt="example3" title="">
       <table>
            <tbody><tr>
              <th></th>
              <td></td>
       </tbody>
       </table>
   </div>

I only want to select the attributes "alt" values "example1, example2, example3" of images. How can I get them.