ช่วยเขียนโค้ด checkbox Enable/Disable <select> แบบลูปให้ทีค่ะ

<table width='100%' border='0'>
<?PHP
	$slType = mysql_query("SELECT * FROM test_type ORDER BY typeID ASC");
	$nrType = mysql_num_rows($slType);
		for($i=0;$i<$nrType;$i++){
			$rsType = mysql_fetch_array($slType);
?>
				<tr>
					<th width='20px'><input type="checkbox" name="list_type[]" id="list_type<?=$i;?>" value='<? echo $rsType['typeID']; ?>' OnClick="if(this.checked){document.form1.num<?=$i;?>.disabled=true;}else{document.form1.num<?=$i;?>.disabled=false;}"/></td>
					<th width='70px' align='right' style='color:#990000;'>วิชาที่ <? echo $i+1; ?> :</th>
					<td><span title='<? echo $rsType['typeNameEn']; ?>'><? echo $rsType['typeNameTh']; ?></span></td>
					<td>
						<select name='num[]' id='num<?=$i;?>'>
							<option type='0'>0</option>
							<option type='0'>0</option>
						</select>
					</td>
				</tr>
<?PHP } ?>	
</table>