为何点击下拉没反应
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<title>Document</title>
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<style>
body{
padding-top: 70px;
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<body>
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<nav class="navbar navbar-default navbar-inverse navbar-fixed-top" role="navigation">
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<div>
<a href="##">
呵呵呵呵呵
</a>
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<ul class="nav navbar-nav navbar-right">
<li><a href="#">导航1</a></li>
<li><a href="#">导航2</a></li>
<li>
<a href="##" data-toggle="dropdown">导航下拉<span></span></a>
<ul>
<li><a href="##">1</a></li>
<li><a href="##">2</a></li>
<li><a href="##">3</a></li>
<li><a href="##">4e</a></li>
</ul>
</li>
<li><a href="#">导航4</a></li>
</ul>
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