```
<form action="1.html">
    <input type="radio" id="check1" name="check" />
    <input type="radio" id="check2" name="check" />
</form>

```

What I want to implement is :

when "check2" is checked,change "action" value to "2.html"

when "check1" is checked,change "action" value back to "1.html"