??问题??如何实现该函数...

1@LANGUAGE="VBSCRIPT" CODEPAGE="936"

1<script language="javascript">   
2function IsSelect(){   
3//如何实现单击aaaaa而不是单击单选按钮，就将所在的单选按钮选中   
4//如何实现单击bbbbb将所在的单选按钮选中   
5//以下依次   
6  
7}   
8</script>

1<html>
2<head>
3<title>Untitled Document</title>
4<meta content="text/html; charset=utf-8" http-equiv="Content-Type"/>
5</head>
6<body>
7<form action="" method="post" name="form1">

for i=1 to 4

 1<table border="1" width="75%">
 2<tr>
 3<td onclick="IsSelect()"><input name="r```
 4=i
 5```" type="radio" value="radiobutton"/>aaaaa</td>
 6</tr>
 7<tr>
 8<td onclick="IsSelect()"><input name="r```
 9=i
10```" type="radio" value="radiobutton"/>bbbbb</td>
11</tr>
12<tr>
13<td onclick="IsSelect()"><input name="r```
14=i
15```" type="radio" value="radiobutton"/>ccccc</td>
16</tr>
17<tr>
18<td onclick="IsSelect()"><input name="r```
19=i
20```" type="radio" value="radiobutton"/>ddddd</td>
21</tr>
22</table><br/><span></span>

1</form>
2</body>
3</html>

---------------------------------------------------------------

1@LANGUAGE="VBSCRIPT" CODEPAGE="936"

1<script language="javascript">   
2function IsSelect(src){   
3src.children[0].checked=src.children[0].checked?false:true   
4}   
5</script>

 1<html>
 2<head>
 3<title>Untitled Document</title>
 4<meta content="text/html; charset=utf-8" http-equiv="Content-Type"/>
 5</head>
 6<body>
 7<form action="" method="post" name="form1">
 8<table border="1" width="75%">
 9<tr>
10<td onclick="IsSelect(this)"><input name="r" type="radio" value="radiobutton"/>aaaaa</td>
11</tr>
12<tr>
13<td onclick="IsSelect(this)"><input name="r" type="radio" value="radiobutton"/>bbbbb</td>
14</tr>
15<tr>
16<td onclick="IsSelect(this)"><input name="r" type="radio" value="radiobutton"/>ccccc</td>
17</tr>
18<tr>
19<td onclick="IsSelect(this)"><input name="r" type="radio" value="radiobutton"/>ddddd</td>
20</tr>
21</table><br/><span></span>
22</form>
23</body>
24</html>