radio是只限于两个之间的单选吗？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>单选框、复选框</title>
</head>
<body>
<form action="save.php" method="post" >
<label>性别:</label>
<label>男</label>
<input type="radio" value="1" name="gender" />
<label>女</label>
<input type="radio" value="2" name="gender" />
<label>公<label>
<input type="radio" value="3" name="gender"/>
</form>
</body>
</html>
