<script type="text/javascript" src="scripts/jquery.js"></script>

    <style type="text/css">
        .aaaa
        {
            float: left;
            list-style: none;
            margin: 10px;
        }
    </style>

    <script type="text/javascript">
        $(function() {
            $('#plays').addclass('aaaa');//对象不支持此属性或方法
        });
    </script>