幫我看一下哪里錯了，為什么應該在第二層的mainbody最后卻顯示在了第一層

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<html?xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8"?/>
<title>幾米的書</title>
<style?type="text/css">
*{margin:0;padding:0}<!--代碼初始化?-->
#header{width:100%;height:200px;border:1px?solid?red;}
#mainbody{width:100%;height:200px;border:1px?solid?yellow;}
#footer{width:100%;height:200px;border:1px?solid?green;}

.content{border:4px?solid?#badbdb;padding:34px?15px?15px;width:770px}
.book{background:url(file:///E|/flash%E7%B4%A0%E6%9D%90/400%E4%B8%AA%E9%AB%98%E6%B8%85%E8%83%8C%E6%99%AF/1.jpg)no-repeat?#0F9}
img{margin:10px?18px;border:1px?solid?#red}
</style>
</head>

<body>
<div?id="header"></div><!--id選擇器有唯一性?-->
<div?id="mainbody">
????<div?class="content?book"><!--?追加樣式book-->
????<img?src="file:///E|/圖片/桌面壁紙/2fdda3cc7cd98d1043500190213fb80e7aec908e.jpg"?width="80"?height="80"?/>
????<img?src="file:///E|/圖片/桌面壁紙/3UB7H5XFR403_1280x1024.jpg"?width="80"?height="80"?/>
????<img?src="file:///E|/圖片/桌面壁紙/51b3eda827993.jpg"?width="80"?height="80"?/>
????<img?src="file:///E|/圖片/桌面壁紙/96c4d41ebdabb52d56a82de3e6c0844c.jpg"?width="80"?height="80"?/><img?src="file:///E|/圖片/桌面壁紙/51c5338f46a36.jpg"?width="80"?height="80"?/>
????</div>
</div>
<div?id="footer"></div>
</body>
</html>