var speed3=25//速度数值越大速度越慢
dem2.innerHTML=dem1.innerHTML
function Marquee(){
if(dem2.offsetWidth-dem.scrollLeft<=0)
dem.scrollLeft-=dem1.offsetWidth
else{
dem.scrollLeft++
}
}
var MyMar=setInterval(Marquee,speed3)
dem.onmouseover=function() {clearInterval(MyMar)}
dem.onmouseout=function() {MyMar=setInterval(Marquee,speed3)}