怎么实现radio的显示与隐藏

    <?php foreach($list as $k=>$v){ ?><br />
                       <ul><br />
                    <li><?php echo $v['id'];?>、<?php echo $v['sub'];?></li><br />
                    <li><input type="radio" name="<?php echo $k['id'];?>" value="Y" />是</li><br />
                    <li><input type="radio" name="<?php echo $k['id'];?>" value="N" />否</li><br />
                    <li><input type="radio" name="<?php echo $k['id'];?>" value="?" />？</li><br />
               </ul><br />
                       <?php } ?><br />