function showSub(id) {
		var ddArray = document.getElementsByTagName("dd");
		if(id == 'act')
		{//only take effect on subMenu
			for(var i = 0; i < ddArray.length; i++)
			{
				if(ddArray[i].id == "subMenu")
				{
					if(ddArray[i].style.display == "" || ddArray[i].style.display == "none")
					{
						ddArray[i].style.display = "block";
					}
					else
					{
						ddArray[i].style.display = "none";
					}
				}
			}
		} else if(id == 'intro')
		{
			for(var i = 0; i < ddArray.length; i++)
			{
				if(ddArray[i].id == "subMenuIntro")
				{
					if(ddArray[i].style.display == "" || ddArray[i].style.display == "none")
					{
						ddArray[i].style.display = "block";
					}
					else
					{
						ddArray[i].style.display = "none";
					}
				}
			}
		}
	}// JavaScript Document