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                        /玩轉Bootstrap（基礎）

為什么我的頁面沒有效果呢粘貼別人的代碼也沒有效果

<!DOCTYPE?HTML>
<html>
<head>
<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8">
<title>菜單標題</title>
<link?rel="stylesheet"?>
<link?rel="stylesheet"?href="style.css">
</head>

<body>
<div?class="dropdown">
??<button?class="btn?btn-default?dropdown-toggle"?type="button"?id="dropdownMenu1"?data-toggle="dropdown">
????下拉菜單
????<span?class="caret"></span>
??</button>
??<ul?class="dropdown-menu"?role="menu"?aria-labelledby="dropdownMenu1">
????<li?role="presentation"?class="dropdown-header">第一部分菜單頭部</li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
????<li?role="presentation"?class="divider"></li>
????<li?role="presentation"?class="dropdown-header">第二部分菜單頭部</li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">下拉菜單項</a></li>
??</ul>
</div>?
<div?class="dropdown">
??<button?class="btn?btn-default?dropdown-toggle"?type="button"?id="dropdownMenu1"?data-toggle="dropdown">
????食物
????<span?class="caret"></span>
??</button>
??<ul?class="dropdown-menu"?role="menu"?aria-labelledby="dropdownMenu1">
????<li?role="presentation"?class="dropdown-header">水果</li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">蘋果</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">香蕉</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">梨</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">桃</a></li>
????<li?role="presentation"?class="divider"></li>
????<li?role="presentation"?class="dropdown-header">蔬菜</li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">芹菜</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">蘿卜</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">茄子</a></li>
????<li?role="presentation"?class="divider"></li>
????<li?role="presentation"?class="dropdown-header">主食</li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">米飯</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">饅頭</a></li>
????<li?role="presentation"><a?role="menuitem"?tabindex="-1"?href="#">面條</a></li>
??</ul>
</div>?
??<script?src="http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>
??<script?src="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>?

</body>
</html>

點擊按鈕沒有效果為什么呢是我的原因嗎