function showHide(id)
{
	var el=document.getElementById(id);
	var bExpand=false;
	var images=el.getElementsByTagName("img");
	if(images[0].src.indexOf("minus.gif")!=-1)
	{
		bExpand=false;  
		images[0].src="/images/plus.gif"
	}
	else
	{
		bExpand=true;
		images[0].src="/images/minus.gif" 
	}
	var subs=el.lastChild;
	if(bExpand)
	{
		subs.style.display="block";//设置<ul>元素为隐藏
	}
	else
	{
		subs.style.display="none";//设置<ul> 元素为显示
	}
}