这个代码有毒
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>企业网站实践</title>
<link href="css/index.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" charset="gb2312" src="js/setHomeSetFav.js"></script>
<script type="text/javascript" src="js/myfocus-2.0.1.min.js"></script>
<!--<script type="text/javascript">
myFocus.set({
id:'picBox'
})
</script>-->
</head>
<body>
<div class="top">
<div class="top_content">
<ul>
<a href="#"><li>联系我们</a></li>
<a href="#"><li>加入收藏</a></li>
<a href="#"><li>设为首页</a></li>
</ul>
</div>
</div>
<div class="wrap">
<!--Star-logo-->
<div class="logo">
<div class="logo_left">
<img src="images/logo.jpg" alt="慕课网" />
</div>
<div class="logo_right">
<img src="images/tel.jpg" alt="服务热线" />24小时服务热线
<span class="tel">028-123456789</span>
</div>
</div>
<!--Stop-logo-->
<!--Start-nav-->
<div class="nav">
<div class="nav_left"></div>
<div class="nav_mid">
<div class="nav_mid_left">
<ul>
<li><a href="#">首页</a></li>
<li><a href="#">关于课程</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 method="post" action="#">
<input type="text" value="" placeholder="搜索框" class="serch" />
</form>
</div>
</div>
<div class="nav_right"></div>
</div>
<!--Stop-nav-->
<div class="ad" id="picBox">
<!--<div class="loading"><img src="images/loading.gif" alt="图片加载中" /></div>-->
<div class="pic">
<ul>
<li><img src="images/ad2.jpg" /></li>
<li><img src="images/ad3.jpg" /></li>
<li><img src="images/ad4.jpg" /></li>
</ul>
</div>
</div>
<div class="main">
<!--Start-news-->
<div class="news">
<!--S-title-->
<div class="title">
<h2 class="title_left">新闻中心</h2>
<span class="title_right"><a href="#">More>></a></span>
</div>
<!--S-title-->
<!--S-pic_news-->
<div class="pic_news">
<img src="images/news.jpg" />
<h2><a href="#">520慕课女神喊你来表白</a></h2>
<p>活动时间5/20-5/25<br />中奖公布时间：5/26<br /><a href="#">Learn More>></a></p>
</div>
<!--S-pic_news-->
<!--S-news_list-->
<div class="news_list">
<ul>
<li>
<a href="#">"有为屌丝"在路上</a>
<span>2017-3-27</span>
</li>
<li>
<a href="#">"有为屌丝"在路上</a>
<span>2017-3-27</span>
</li>
<li>
<a href="#">"有为屌丝"在路上</a>
<span>2017-3-27</span>
</li>
</ul>
</div>
<!--S-news_list-->
</div>
<!--StopNews-->
<div class="course">
<div class="title">
<h2 class="title_left">课程中心</h2>
<span class="title_right"><a href="#">More>></a></span>
</div>
<div class="course_pic">
<img src="images/css.jpg" />
<h2><a href="#">圆角进化论</a></h2>
<p>CSS圆角的实现，经历了三大发展阶段：背景图片、CSS2.0+HTM、CSS3.0圆角属性。本案例详细交接
每一种实现方式，并对实现的优缺点进行比较</p>
</div>
<div class="course_type">
<ul>
<li>PHP开发</li>
<li>Java开发</li>
<li>Web开发</li>
<li>Android开发</li>
</ul>
</div>
</div>
<div class="sidebar">
<div class="video">
<div class="title">
<h2 class="title_left">媒体聚焦</h2>
</div>
<div class="video_cotent">
<embed src='http://player.youku.com/player.php/sid/XMjY1Mzc4MjU3Ng==/v.swf'
allowFullScreen='true' quality='high' width='220px' height='140px' align='middle'
allowScriptAccess='always' type='application/x-shockwave-flash'></embed>
</div>
</div>
<div class="sidebar_ad">
<img src="images/app.jpg" />
</div>
</div>
</div>
<div class="copyright"></div>
</body>
</html>
一直是按照视频写的，为啥class="copyright"的盒子在F12下看到的是以wrap为父元素的，这是为什么？谁知道吗？是代码少了一些闭合标签吗？不知道原因
