var speed=40; //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)};