<table width="100%" border="0" cellspacing="0" cellpadding="0" id="theTable">
<tr>
<td id='aaa'><input type='text'></td>
</tr>
</table><input type='button' value='添加一行' onclick="document.all.aaa.innerHTML += '<br><input type=\'text\'>'">
<tr>
<td id='aaa'><input type='text'></td>
</tr>
</table><input type='button' value='添加一行' onclick="document.all.aaa.innerHTML += '<br><input type=\'text\'>'">
document.getElementById("tr"+"test").appendChild(objTd);
document.getElementById("tr"+"test").removeChild(objTd);