依旧是下拉框问题（100分在线等待）

Question

<form method=post>
<select onchange=chg() name=a>
<option>1
<option>2
<option>3
</select>
<select name=b>
<option>1
<option>2
<option>3
</select>
</form>
<script>
function chg(){//让页面刷新一下
document.forms[0].submit();
}
</script>

Answer 1

<form method=post>
<select onchange=chg() name=a>
<option>1
<option>2
<option>3
</select>
<select name=b>
<option>1
<option>2
<option>3
</select>
</form>
<script>
var arr=[["1","2","3"],["a","b","c"],["m","n","k"]]
function chg(){
var i=document.all.a.selectedIndex
with(document.all.b){
length=0;
for(j=0;j<arr[i].length;j++)
options.add(new Option(arr[i][j],arr[i][j]))
}
}
</script>