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哪位大神能够指点迷津？焦点图不出来

<!DOCTYPE html>
<html>
   <head>
       <meta charset="utf-8" />
       <link rel="stylesheet" href="css/qwe.css" type="text/css"/>
       <script src="js/setHomeSetFav.js" type="text/javascript" charset="gb2312"></script>
       <script type="text/javascript" src="js/myfocus-2.0.1.min.js" charset="utf-8"></script>
       <script type="text/javascript" src="js/mf-pattern/mF_fancy.js" ></script>
       <link rel="stylesheet" href="js/mf-pattern/mF_fancy.css" type="text/css" />
       <script type="text/javascript">
           myfocus.set({
               id:'picBox'
           })
       </script>
       <title>导航</title>
   </head>
   <body>
       <div class="top">
           <div class="top_content">
               <ul>
                   <li><a href="#">联系我们</a></li>
                   <li><a href="#" onclick="AddFavorite(window.location,document.title)">加入收藏</a></li>
                   <li><a href="#" onclick="SetHome(window.location)">设为首页</a></li>
               </ul>
           </div>
       </div>
       <div class="wrap">
           <div class="logo">
               <div class="logo_left">
                   <img src="img/logo.jpg" alt="慕课网" />
               </div>
               <div class="logo_right">
                   <img src="img/tel.jpg" alt="服务热线" />24小时服务热线：<span class="tel">124-253-2353</span>
               </div>
           </div>

           <div class="nav">

               <div class="nav_mid">
                   <div class="nav_mid_left">
                       <ul>
                           <li><a href="#">首页</a></li>
                           <li><a href="#">关于慕课</a></li>
                           <li><a href="#">新闻动态</a></li>
                           <li><a href="#">课程中心</a></li>
                           <li><a href="#">在线课程</a></li>
                           <li><a href="#">人才招聘</a></li>
                       </ul>
                   </div>
                   <div class="nav_mid_right">
                       <form action="" method="post">
                           <input type="text" class="search_text"/>
                       </form>
                   </div>
               </div>
           </div>
           <div class="ad" id="picBox">
               <div class="loading"><img src="img/loading.gif" alt="图片加载中"/></div>
               <div class="pic">
                   <ul>
                       <li><img src="img/ad2.jpg"/></li>
                       <li><img src="img/ad3.jpg"/></li>
                       <li><img src="img/ad4.jpg"/></li>
                   </ul>

               </div>
           </div>
       </div>

   </body>
</html>

CSS代码

*{
   margin: 0;
   padding: 0;
   font-size: 12px;
}

body{
   background-color: #F5F5F5;
}
.top{
   width: 100%;
   height: 27px;
   background: url(../img/top_bg.jpg) repeat-x: ;
}
.top_content{
   width: 1000px;
   margin: 0 auto;
}
.top_content li{
   list-style-image: url(../img/li_bg.gif);
   float: right;
   width: 70px;
   line-height: 27px;
}
.top_content a:link,.top_content a:visited{
   color: #8E8E8E;
   text-decoration: none;
}
.top_content a:hover,.top_content a:active{
   color: #900;
   text-decoration: none;
}
.wrap{
   width: 1000px;
   margin: 0 auto;
}

.logo{
   height: 80px;
   background-color: #FFFFFF;
}

.logo_left{
   width: 200px;
   float: left;
}

.logo_right{
   width: 300px;
   float: right;
   height: 28px;
   margin-top: 30px;
}
.logo_right img{
   vertical-align: middle;
   margin-right: 10px;
}

.tel{
   font-family: "微软雅黑";
   font-size: 16px;
   color: #C00;
}
.nav{
   height: 40px;
}

.nav_mid{
   width:1000px;
   background:url(../img/nav_bg.jpg)repeat-x;
   float: left;
   height: 40px;
}

.nav_mid_left,.nav_mid_right{

   float: left;
}
.nav_mid_left{
   width: 700px;
}
.nav_mid_right{
   width: 300px;
}
.nav_mid_left li{
   width: 100px;
   list-style-type: none;
   float:left;
   text-align: center;
   line-height: 40px;
}
.nav_mid_left a:link,.nav_mid_right a:visited{
   text-decoration: none;
   color:#FFF;
   font-size: 16px;
   font-family: "微软雅黑";

}
.nav_mid_left a:hover,.nav_mid_right a:active{
   text-decoration: none;
   color: gold;
   font-size: 16px;
   font-family: "微软雅黑";
}
.search_text{
   width:190px;
   height: 25px;
   margin-top: 5px;
   background:url(../img/search.jpg) no-repeat right center;
   background-color: #FFF;
   padding-right: 25px;
   border: 1px solid #FFF;
}
.ad{
   height:310px;
   overflow:hidden;
}