var speed3=60//速度数值，越大速度越慢
var t=false; 
var id="aa"; 

function Marquee(){
	if(document.getElementById("demo2").offsetWidth-document.getElementById("demo").scrollLeft<=0) 
		document.getElementById("demo").scrollLeft-=document.getElementById("demo1").offsetWidth;
	else{ 
		document.getElementById("demo").scrollLeft++;
	} 	
	t=false; 
} 
function RMarquee(){  
	if(document.getElementById("demo").scrollLeft<=0) 
	    document.getElementById("demo").scrollLeft+=document.getElementById("demo2").offsetWidth;
	else{ 
	    document.getElementById("demo").scrollLeft--;
	} 
	t=true;
} 
function clickdiv(){ 
	window.clearInterval(MyMar) 
	Marquee(); 
} 
function Rclickdiv(){ 
	window.clearInterval(MyMar);
	RMarquee();
}