这个计时器就竟哪儿有错！！！肯请大家指点！！！！

 1<script language="javascript">   
 2function time_(t)   
 3{   
 4var mm,ss;   
 5  
 6mm=parseInt(t/60);   
 7ss=t % 60;   
 8if(mm<10) mm='0'+mm;   
 9if(ss<10) ss='0'+ss;   
10str=mm+'分'+ss+'秒';   
11form1.test1.value=str;   
12t=t-1;   
13if(t==0) form1.submit();   
14setTimeout('time_()',1000);   
15}   
16</script>

 1<form action="test.asp" method="post" name="form1">
 2<font style="font-size:13px">时间还剩:</font><input name="test1" type="text"/>
 3<input onclick="time_(60)" type="button" value="计时1"/>   
 4  
 5为何老是出错：显示：NaN分NaN 秒   
 6  
 7可是如果换成   
 8<script language="javascript">   
 9var t;   
10t=60;   
11function time_()   
12....   
13....   
14<input type="button" value="计时1" onclick="time_()">   
15这是在论坛上搜到的一个计时间的代码，我想以参数形式把要计的时候传到 time_()里去，可是就是不行！！！   
16请大家帮我！！！！   
17\---------------------------------------------------------------   
18  
19setTimeout('time_(' +t+')',1000);   
20  
21  
22<script language="javascript">   
23function time_(t)   
24{   
25var mm,ss;   
26  
27mm=parseInt(t/60);   
28ss=t % 60;   
29if(mm<10) mm='0'+mm;   
30if(ss<10) ss='0'+ss;   
31str=mm+'分'+ss+'秒';   
32form1.test1.value=str;   
33t=t-1;   
34if(t==0) form1.submit();   
35setTimeout('time_(' +t+')',1000);   
36}   
37</script>
38<form action="test.asp" method="post" name="form1">
39<font style="font-size:13px">时间还剩:</font><input name="test1" type="text"/>
40<input onclick="time_(60)" type="button" value="计时1"/></form></form>