function _fresh()
{
	var endtime=new Date("May 1, 2012 12:00:00");
	var nowtime = new Date();
	var leftsecond=parseInt((endtime.getTime()-nowtime.getTime())/1000);
	if(leftsecond<0){leftsecond=0;}
	__d=parseInt(leftsecond/3600/24);
	__h=parseInt((leftsecond/3600)%24);
	__m=parseInt((leftsecond/60)%60);//2008-3-12改正，原来将60写成24了
	__s=parseInt(leftsecond%60);
	document.getElementById("_lefttime").innerHTML=__d+"天 "+__h+"小时"+__m+"分"+__s+"秒";
}
_fresh()
setInterval(_fresh,1000);