function related(n){	
bigname=["软件","硬件"]	
smallname1=["操作系统","设计软件","数据库","office","浏览器","邮件","病毒","编程","Intranet应用","Internet应用","音频视频","软件其他"]	
smallname2=["cpu","内存","主板","显卡","硬盘","显示器","打印机","网络产品","电脑超频","硬件其他"]	
 with(document){	
     var big_num=formqa.elements["table_b"].selectedIndex	
     var big_class=formqa.elements["table_b"]	
     var small_class=formqa.elements["table_s"]	
     selected_num=parseInt(big_class.options[big_num].value)	
     switch(selected_num)	
     {	
         case 0:	
           small_class.options[0]=new Option("全部",0)	
           break;	
         case 1:	
           for(var i=smallname1.length-1;i>=0;i--)	
           {	
             small_class.options[smallname1.length-1-i]=new Option(smallname1[smallname1.length-1-i],smallname1.length-1-i)	
           }	
           break;	
         case 2:	
           for(var i=smallname2.length-1;i>=0;i--)	
           {	
             small_class.options[smallname2.length-1-i]=new Option(smallname2[smallname2.length-1-i],smallname2.length-1-i)	
           }	
           break;	
         default:	
           for(var i=0;i<9;i++)	
           {	
             small_class.options[i]=null	
           }	
     }	
     small_class.options[0].selected=true	
 }	
}