都是本地引入，是不是下错了，没有下拉列表
<link rel="stylesheet" href="css/bootstrap.min.css">
<title>无标题文档</title>
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-4">.col-md-1</div>
<div class="col-md-4 col-md-offset-4">.col-md-8</div>
</div>
</div>
<div class="container">
<div class="row">
<div class="col-md-4 col-md-push-8">.col-md-4</div>
<div class="col-md-8 col-md-pull-4">.col-md-8</div>
</div>
</div>
<div class="dropdown">
<button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown">
下拉菜单
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li>
</ul></div>
<script src="jQuery/jquery-3.3.1.js"></script>
<script src="jQuery/js/bootstrap.min.js"></script>
</body>
