单选组和文本框


<form id="form1" name="form1" method="post" action="">
      <input type="radio" name="Radio" value="1" id="Radio_0" />1<br />
    
      <input type="radio" name="Radio" value="2" id="Radio_1" />2<br />
    
      <input type="radio" name="Radio" value="3" id="Radio_2" />3<br />
    
      <input type="radio" name="Radio" value="4" id="Radio_3" />4 
      <input type="text" name="answer_2" id="answer_2" onclick="document.getElementById('Radio_3').checked=true;" />
      <br /></form>