var speed=50 
   scroll_top2.innerHTML=scroll_top1.innerHTML
   function Marquee1(){ 
   if(scroll_top2.offsetTop-scroll_top.scrollTop<=0)   
   scroll_top.scrollTop-=scroll_top1.offsetHeight
   else{ 
   scroll_top.scrollTop++;
   } 
   } 
   var MyMar1=setInterval(Marquee1,speed)//设置定时器 
   scroll_top.onmouseover=function() {clearInterval(MyMar1)} 
   scroll_top.onmouseout=function(){MyMar1=setInterval(Marquee1,speed)}