<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>模态弹出窗的使用</title>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
</head>
<body>
<!--下面是代码任务部分-->
<!-- href触发模态弹出窗元素 -->
<a class="btn btn-primary" data-toggle="modal" href="#mymodal-link">通过链接href属性触发</a>
<!-- 模态弹出窗内容 -->
<div class="modal" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel" aria-hidden="true" id="mymodal-link">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">×</span><span class="sr-only">Close</span></button>
<h4 class="modal-title">模态弹出窗标题</h4>
</div>
<div class="modal-body">
<p>模态弹出窗主体内容</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
<button type="button" class="btn btn-primary">保存</button>
</div>
</div>
</div>
</div>
<!-- data-target触发模态弹出窗元素 -->
<button class="btn btn-primary" type="button" data-toggle="modal" data-target="#mymodal-data">通过data-target触发</button>
<!-- 模态弹出窗内容 -->
<div class="modal" id="mymodal-data" tabindex="-1" role="dialog" aria-labelledby="mySmallModalLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">×</span><span class="sr-only">Close</span></button>
<h4 class="modal-title">模态弹出窗标题</h4>
</div>
<div class="modal-body">
<p>模态弹出窗主体内容</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
<button type="button" class="btn btn-primary">保存</button>
</div>
</div>
</div>
</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>
script的地址有问题，改成下面这个就行了
<script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script>
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>