<div style="width:500px; height:500px;">

 <div style="margin-top:20px;">

     <input type="radio" name="sure" id="s1" οnclick="KeYong()" />同意

        <input type="radio" name="sure" id="s2" οnclick="BuKeYong()" />不同意

    </div>

    <div style="margin-top:30px">

     <input type="submit" value="确定" id="btn" style="width:100px; height:35px;" disabled="disabled" />

    </div>

</div>

 

<script type="text/javascript">

 　　function KeYong()

 {

  　　//找到按钮

  　　var a = document.getElementById("btn");

  

　　  //操作按钮属性

 　　 a.removeAttribute("disabled");

 }

 　　function BuKeYong()

 {

  　　var a = document.getElementById("btn");

  　　a.setAttribute("disabled","disabled");

 }

</script>