<form id="form1" name="form1" method="post" action="">
<input type="checkbox" name="checkbox" value="checkbox" onclick="if(document.all.s.disabled)document.all.s.disabled=false;else document.all.s.disabled=true;"/>
<select name="s" size="1" disabled>
<option>1</option>
<option>2</option>
<option>3</option>
</select>
<input type="checkbox" name="checkbox" value="checkbox" onclick="if(document.all.s.disabled)document.all.s.disabled=false;else document.all.s.disabled=true;"/>
<select name="s" size="1" disabled>
<option>1</option>
<option>2</option>
<option>3</option>
</select>
function test(o)
{
if(o.checked==false)
{
o.checked=true;
document.all["s1"].disabled=false;
}
else
{
o.checked=false;
document.all["s1"].disabled=true;
}
}
</script>
<body>
<input type=radio id='r1' onclick="test(this);">
<select size=1 id='s1'>
<option value="1">1</option >
</select>
</body>
onclick="s.disabled=!this.checked;"
<select name="nn" size="1" id="nn" disabled>
<option>1</option>
<option>2</option>
<option>3</option>
</select>