<script type="text/javascript" defer="defer">

function $(value)
{
return document.getElementById(value);
}
function ch(s){
var p = new Array(0,1,2);
p[0] = '大学';
p[1] = '高中';
p[2] = '初中';
if(s.value=='0'){
$('n2').options.length = 0;
$('n2').options.add(new Option(p[0],p[0]));
}
if(s.value=='1'){
$('n2').options.length = 0;
$('n2').options.add(new Option(p[1],p[1]));
}
if(s.value=='2'){
$('n2').options.length = 0;
$('n2').options.add(new Option(p[2],p[2]));
}
}
</script>
<table width="400" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="119"><select name="n1" size="10" id="n1" onchange="ch(this)">
<option value="0">大学</option>
<option value="1">高中</option>
<option value="2">初中</option>
</select>
</td>
<td width="281"><select name="n2" size="10" id="n2"><option value="a">a</option>
</select></td>
</tr>
</table>