Are you sure this works? Because I tried this too but it fails. Here's my code:

function checkone(){

            var j=document.getElementById("wb").value;

        var hobby = document.getElementByName("hobby");

        hobby[parseInt(j)-1].checked=true;}

(I'm sorry I have to type English because the computer I'm using isn't installed with a Chinese input method~~)

是不是这个写错了？document.getElementsByTagName("hobby");