<html><head>
<title>New Page 1</title>
<script>
function check()
{
if(f1.d1.options[1].selected)
{
f1.d2.length=0
f1.d2.options.add(new Option("浙江"))
f1.d2.options.add(new Option("江苏"))
}
}
function check1()
{
if(f1.d2.options[0].selected)
{
f1.d3.length=0
f1.d3.options.add(new Option("杭州"))
f1.d3.options.add(new Option("宁波"))
}}
</script>
</head><body><form name=f1 method="POST" action=""> <p><select size="1" name="d1" onchange="check()">
<option>Iran</option>
<option>China</option>
<option>USA</option>
<option>Taiwan</option>
</select><select size="1" name="d2" onchange="check1()">
</select><select size="1" name="d3">
</select></p>
</form></body></html>
<title>New Page 1</title>
<script>
function check()
{
if(f1.d1.options[1].selected)
{
f1.d2.length=0
f1.d2.options.add(new Option("浙江"))
f1.d2.options.add(new Option("江苏"))
}
}
function check1()
{
if(f1.d2.options[0].selected)
{
f1.d3.length=0
f1.d3.options.add(new Option("杭州"))
f1.d3.options.add(new Option("宁波"))
}}
</script>
</head><body><form name=f1 method="POST" action=""> <p><select size="1" name="d1" onchange="check()">
<option>Iran</option>
<option>China</option>
<option>USA</option>
<option>Taiwan</option>
</select><select size="1" name="d2" onchange="check1()">
</select><select size="1" name="d3">
</select></p>
</form></body></html>
1 中国 0
2 浙江 1
3 江苏 1
4 杭州 2
5 宁波 2
6 苏州 1如果江苏也有子类该怎么写?