// JavaScript Document
function zhang(obj,num)
{
 if (obj.className == "x1") return;
 var objname = obj.parentNode;
 var aa = objname.id;
 var objList = objname.getElementsByTagName("li");
	for (var i=0;i<objList.length;i++)
	{
		if(i==num)
		{
			obj.className="x1";
			document.getElementById(aa+i).style.display="block";
		}
		else
		{
			objList[i].className="x";
			document.getElementById(aa+i).style.display="none";
		}
		}
}