function getElementArray(typeString,id){
		var eArray=[];
		var F_obj=document.getElementById(id);
		var children=F_obj.childNodes;
		if(F_obj.nodeType==1){
			for(var i=0;i<children.length;i++)
				{
					if(children[i].nodeType==1&&children[i]!=null){
						for(var o=children[i].firstChild; o!=null; o=o.nextSibling)
						{
							if(o.nodeName.toString().toLowerCase()==typeString){
								eArray.push(o);
							}
						}
					}
				}
			}
		return eArray;
		
		/*
			这种方法更方便，可以节省更多的代码。。。
			var F_obj=document.getElementById(id);
			var children=F_obj.getElementsByTagName(typeString);
		*/
	}
	
	function getFocus(arrayObj1,arrayObj2){
		var focusTime=3000;
		var actor=-1;
		var timer=setInterval(function(){
			var t=(actor+1)>=arrayObj1.length?0:actor+1;
			onFocus(arrayObj1[t]);
		},focusTime);
		
		for(var i=0;i<arrayObj1.length;i++)
		{
			arrayObj1[i].onmouseover=function(){
				onFocus(this);
				clearInterval(timer);
			};
			arrayObj2[i].onmouseover=function(){
				onFocus(this);
				clearInterval(timer);
			};
			arrayObj1[i].onmouseout=function(){
					timer=setInterval(function(){
					var f=(actor+1)>=arrayObj1.length?0:actor+1;
					onFocus(arrayObj1[f]);
				},focusTime);};
			arrayObj2[i].onmouseout=function(){
					timer=setInterval(function(){
					var f=(actor+1)>=arrayObj1.length?0:actor+1;
					onFocus(arrayObj1[f]);
				},focusTime);};
		}
		
		function onFocus(obj){
			for(var i=0;i<arrayObj1.length;i++)
			{
				if(arrayObj1[i].className=='selected'){
					arrayObj1[i].className=null;
				}
				if(arrayObj2[i].className=='selected'){
					arrayObj2[i].className=null;
				}
				if(obj==arrayObj1[i])
				{
					actor=i;
					arrayObj1[i].className='selected';
					arrayObj2[i].className='selected';
				}
				if(obj==arrayObj2[i])
				{
					actor=i;
					arrayObj1[i].className='selected';
					arrayObj2[i].className='selected';
				}
			}		
		}
	}
	
	function img_roll(typeString1,typeString2,id1,id2){
		var eArr1=getElementArray(typeString1,id1);
		var eArr2=getElementArray(typeString2,id2);
		getFocus(eArr1,eArr2);
	}