//function menu_on(menuName) 	//当鼠标经过时，显示菜单
function menu_on(menuName)
{
	switch(menuName)
	{	
		case "Layer_Services":
			Layer_Services.style.visibility="visible";
			Layer_news.style.visibility="hidden";
			break;
		
		case "Layer_news":
			Layer_Services.style.visibility="hidden";
			Layer_news.style.visibility="visible";
			break;
			
		default:
			alert("您的访问已受限制！");
	}
}

function menu_off()	//当鼠标离开时，关闭菜单
{
			Layer_Services.style.visibility="hidden";
			Layer_news.style.visibility="hidden";
}