<select name="bid" size="1" onChange="redirect(this.options.selectedIndex)">
<option value="文件下载">文件下载</option>
<option value="常见问题解答">常见问题解答</option>
</select>
<select name="lei" size="1">
<option value="网络软件">网络软件</option>
<option value="多媒体类">多媒体类</option>
<option value="安全相关">安全相关</option>
<option value="系统工具">系统工具</option>
<option value="图形图象">图形图象</option>
<option value="应用软件">应用软件</option>
<option value="其它类别">其它类别</option>
</select>
<script>
<!--
/*
Double Combo Script Credit
By Website Abstraction (www.wsabstract.com)
Over 200+ free JavaScripts here!
*/
var groups=document.Login.bid.options.length
var group=new Array(groups)
for (i=0; i<groups; i++)
group[i]=new Array()
group[0][0] = new Option("网络软件","网络软件")
group[0][1] = new Option("多媒体类","多媒体类")
group[0][2] = new Option("安全相关","安全相关")
group[0][3] = new Option("系统工具","系统工具")
group[0][4] = new Option("图形图象","图形图象")
group[0][5] = new Option("应用软件","应用软件")
group[0][6] = new Option("其它类别","其它类别")

group[1][0] = new Option("邮件邮箱","邮件邮箱")
group[1][1] = new Option("虚拟主机","虚拟主机")
group[1][2] = new Option("域名服务","域名服务")
group[1][3] = new Option("其它问题","其它问题")

var temp=document.Login.lei
function redirect(x){
for (m=temp.options.length-1;m>0;m--)
temp.options[m]=null
for (i=0;i<group[x].length;i++){
temp.options[i]=new Option(group[x][i].text,group[x][i].value)
}
temp.options[0].selected=true
}
function go(){
location=temp.options[temp.selectedIndex].value
}
//-->
</script>