<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8"> 
        <title>菜鸟教程(runoob.com)</title> 
        <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">  
        <script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
        <script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>
    </head>
    <body>

        <div class="container">
            <h2>实例</h2>
            <p> .show 类强制一个元素显示:</p>
            <p class="show">该段落强制显示</p>
            <p> .hidden 类强制一个元素隐藏 :</p>
            <p class="hidden">该段落强制隐藏</p>      
        </div>

    </body>
</html>