我如何获得下表变量中的所有第一个 td
<table cellpadding="0" cellspacing="0" border="0" width="100%" class="myTable">
<tr >
<td>785.1 </td>
<td>do not pick me</td>
</tr>
<tr >
<td>427.31</td>
<td>do not pick me</td>
</tr>
<tr >
<td>780.2</td>
<td>do not pick me</td>
</tr>
<tr>
</table>