var speed1 = 50;//速度，值越大越慢
var demo1a = document.getElementById("ddd");
var demo21a = document.getElementById("ddt2");
var demo11a = document.getElementById("ddt1");
var c11a = document.getElementById("CC1");
var c21a = document.getElementById("CC2");
c21a.innerHTML = c11a.innerHTML;
function Marquee1()
{
    if(demo21a.offsetHeight - demo1a.scrollTop <= 0)
    {
        demo1a.scrollTop = demo1a.scrollTop - demo11a.offsetHeight;
    }
    else
    {
        demo1a.scrollTop = demo1a.scrollTop + 1;
    }
}
var MyMar1 = setInterval(Marquee1,speed1);
demo1a.onmouseover = function(){ clearInterval(MyMar1); }
demo1a.onmouseout = function(){ MyMar1 = setInterval(Marquee1,speed1); }