var speed=30;//数字越大速度越慢
	var tab=document.getElementById("demo");
	var tab1=document.getElementById("demo1");
	var tab2=document.getElementById("demo2");
	tab2.innerHTML=tab1.innerHTML;
	function Marquee(){
	if(tab2.offsetWidth-tab.scrollLeft<=0)
	tab.scrollLeft-=tab1.offsetWidth
	else{
	tab.scrollLeft++;
	}
	}
	var MyMar=setInterval(Marquee,speed);
	tab.onmouseover=function(){clearInterval(MyMar)};
	tab.onmouseout=function(){MyMar=setInterval(Marquee,speed)};