        <!--
        var speed=50; //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)};
        -->