startclock()
var  timerID  =  null;
var  timerRunning  =  false;
function  showtime()  
{
	Today  =  new  Date();
	var  NowHour  =  Today.getHours();
	var  NowMinute  =  Today.getMinutes();
	var  NowMonth  =  Today.getMonth();
	var  NowDate  =  Today.getDate();
	var  NowYear  =  Today.getYear();
	var  NowSecond  =  Today.getSeconds();
	if  (NowYear  <2000)
	NowYear=1900+NowYear;
Today  =  null;
Hourleft  =  23  -  NowHour           //设置什么时候到期的时间(小时) 24小时制 最高为23
Minuteleft  =  59  -  NowMinute       //设置什么时候到期的时间(分钟) 60分钟制 最高为59
Secondleft  =  59  -  NowSecond	      //设置什么时候到期的时间(秒数)上 60秒钟制最高为59
Yearleft  =  2008  -  NowYear		//设置什么时候到期的年限(某年) 具体为200* 年
Monthleft  =  6  -  NowMonth  -  6	//设置什么时候到期的月份(某月) 
Dateleft  =  15  -  NowDate		//设置什么时候到期的天(某天)
	if  (Secondleft<0)
	{
		Secondleft=60+Secondleft;
		Minuteleft=Minuteleft-1;
	}
	if  (Minuteleft<0)
	{ 
		Minuteleft=60+Minuteleft;
		Hourleft=Hourleft-1;
	}
	if  (Hourleft<0)
	{
		Hourleft=24+Hourleft;
		Dateleft=Dateleft-1;
	}
	if  (Dateleft<0)
	{
		Dateleft=30+Dateleft;
		Monthleft=Monthleft-1;
	}
	if  (Monthleft<0)
	{
		Monthleft=12+Monthleft;
		Yearleft=Yearleft-1;
	}

Temp=+Dateleft+'天 '+Hourleft+'小时 '+Minuteleft+'分 '+Secondleft+'秒'

//document.write(Temp);
document.form1.left.value=Temp;

timerID  =  setTimeout("showtime()",1000);
timerRunning  =  true;
}
var  timerID  =  null;
var  timerRunning  =  false;

function  stopclock  ()  {
if(timerRunning)
clearTimeout(timerID);
timerRunning  =  false;
}
function  startclock  ()  {
stopclock();
showtime();
}