function inc_menu(elId,first) {
	if(!document.getElementsByName(elId)) return false;
	var fMenu = document.getElementsByName(elId);
	var ffff = null;
	//在每个菜单项加入js事件
	for (var i=0,n=fMenu.length; i<n; i++) {
		if(fMenu[i].getElementsByTagName("a")[0].id == first){
			ffff = fMenu[i];	
		}
		fMenu[i].onmouseover=function() {
			if(ffff != null)
				ffff.className = "";
			this.className = "lxs";
		}
		fMenu[i].onmouseout=function() {
			this.className = "";
			if(ffff != null)
				ffff.className = "lxs";
		}
	}
}