// JavaScript Document
 function qiehuan(num){
if (num==3)
{document.getElementById("qh_con3").style.display="block";
document.getElementById("qh_con0").style.display="none";}
else
{document.getElementById("qh_con0").style.display="block";
document.getElementById("qh_con3").style.display="none";}

  for(var id = 0;id<=9;id++)
  {
   if(id==num)
   {
    document.getElementById("mynav"+id).className="nav_on";
   }
   else
   {
    document.getElementById("mynav"+id).className="";
   }
  }
 }