引入4个文件
<script src="YIQI-UI/jquery-2.1.1.min.js"></script>
<link href="YIQI-UI/YIQI-UI.css" rel=stylesheet>

<link type="text/css" href="plus/tab/js_nav.css" rel="stylesheet" />
<script src="plus/tab/js_nav.js"></script>

<div class="menu">
    <ul class="nav">
        
            <li class="item  "><a href="/">网站首页</a></li>
            <li class="item  child"><a href="/?cn-article-2.html">站长动态</a>
                <ul class="nav">
                        <li class="item  "><a href="/?cn-article-38.html">电商微商</a></li>
                        <li class="item  "><a href="/?cn-article-37.html">业内新闻</a></li>         
                </ul>
            </li>
            <li class="item  "><a href="/?cn-product-28.html">科技产品</a></li>
            <li class="item  "><a href="/?cn-photo-4.html">优秀网站</a></li>
            <li class="item  "><a href="/?cn-video-5.html">建站视频</a></li>
            <li class="item  "><a href="/?cn-down-6.html">常用软件</a></li>
            <li class="item  "><a href="/?cn-job-7.html">行业招聘</a></li>
            <li class="item  "><a href="/?cn-about-8.html">关于戴沐</a></li>
            <li class="item  "><a href="?cn-club.html">用户留言</a></li>
                                                
    </ul>
</div>