题目：
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>jQuery选择器筛选器练习</title>
<link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
<link href="https://cdn.bootcss.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet">
<style>
.my-padding {
padding: 10px 0;
}
.my-dark {
background-color: #f5f5f5;
}
.footer {
background: #111;
font-size: 0.9em;
position: relative;
clear: both;
}
.my-white {
color: #ffffff;
}
body {
margin: 0;
}
#progress {
height: 2px;
background-color: #b91f1f;
transition: opacity 500ms linear;
}
#progress.done{
opacity: 0;
}
</style>
</head>
<body>
<div id="progress"></div>
<!--导航栏开始-->
<nav class="navbar navbar-inverse my-nav">
<div class="container">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="http://www.oldboyedu.com/"><strong>OldBoy Edu</strong></a>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li><a href="#">Python学院<span class="sr-only">(current)</span></a></li>
<li><a href="#">Linux学院</a></li>
<li><a href="http://luffy.oldboyedu.com">路飞学城</a></li>
</ul>
<ul class="nav navbar-nav navbar-right">
<li><a href="#">好好学习</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true"
aria-expanded="false">联系我们<span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="#">Jason</a></li>
<li><a href="#">Sean</a></li>
<li><a href="#">Oscar</a></li>
<li role="separator" class="divider"></li>
<li><a href="#">Jason</a></li>
</ul>
</li>
</ul>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</nav>
<!--导航栏结束-->
<div class="container">
<div class="jumbotron">
<div id="i1" class="container">
<h1 class="c1">Jason</h1>
<h1 class="c1">带你学习jQuery</h1>
<p id="p1"><a class="btn btn-primary btn-lg" href="https://q1mi.github.io/Blog/2017/07/10/about_jQuery/"
role="button">查看更多</a></p></div>
</div>
<hr>
<div class="row">
<div class="col-md-12">
<table class="table table-bordered table-striped">
<thead>
<tr>
<th>#</th>
<th>姓名</th>
<th>爱好</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<tr>
<th>1</th>
<td>Jason</td>
<td>学习</td>
<td>
<button class="btn btn-warning">编辑</button>
<button class="btn btn-danger">删除</button>
</td>
</tr>
<tr>
<th>2</th>
<td>Oscar</td>
<td>大饼</td>
<td>
<button class="btn btn-warning">编辑</button>
<button class="btn btn-danger">删除</button>
</td>
</tr>
<tr id="tr3">
<th>3</th>
<td>Egon</td>
<td>吹牛逼</td>
<td>
<button class="btn btn-warning">编辑</button>
<button class="btn btn-danger">删除</button>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<hr>
<div class="row">
<div class="col-md-12">
<form id="f1">
<div class="form-group">
<label for="exampleInputEmail1">邮箱</label>
<input type="email" class="form-control" id="exampleInputEmail1" placeholder="Email">
</div>
<div class="form-group">
<label for="exampleInputPassword1">密码</label>
<input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
</div>
<div class="form-group">
<label for="exampleInputFile">上传头像</label>
<input type="file" id="exampleInputFile">
<p class="help-block">只支持img格式。</p>
</div>
<button id="btnSubmit" type="submit" class="btn btn-default">提交</button>
</form>
</div>
</div>
<hr>
<div class="row">
<div class="col-md-12">
<div class="checkbox-wrapper">
<div class="panel panel-info">
<div class="panel-heading">jQuery学习指南</div>
<div id="my-checkbox" class="panel-body">
<div class="checkbox">
<label>
<input type="checkbox" value="0">
jQuery一点都不难
</label>
</div>
<div class="checkbox">
<label>
<input type="checkbox" value="1" checked>
jQuery一学就会
</label>
</div>
<div class="checkbox">
<label>
<input type="checkbox" value="2">
jQuery就要多练
</label>
</div>
<div class="checkbox">
<label>
<input type="checkbox" value="3" disabled>
jQuery学不好
</label>
</div>
</div>
</div>
</div>
<hr>
<div class="radio-wrapper">
<div class="panel panel-info">
<div class="panel-heading">我来老男孩之后...</div>
<div class="panel-body">
<div class="radio">
<label>
<input type="radio" name="optionsRadios" id="optionsRadios1" value="option1" checked>
我的心中只有学习
</label>
</div>
<div class="radio">
<label>
<input type="radio" name="optionsRadios" id="optionsRadios2" value="option2">
学习真的太TM有意思了
</label>
</div>
</div>
</div>
</div>
</div>
</div>
<hr>
<div>
<i class="fa fa-hand-pointer-o fa-lg fa-rotate-90" aria-hidden="true"></i>
<a class="btn btn-success" href="http://jquery.cuishifeng.cn/">jQuery中文API指南</a>
</div>
<hr>
<div class="row">
<div class="col-md-12">
<h2>练习题：</h2>
<ol id="o1">
<li>找到本页面中id是<code>i1</code>的标签</li>
<li>找到本页面中所有的<code>h2</code>标签</li>
<li>找到本页面中所有的<code>input</code>标签</li>
<li>找到本页面所有样式类中有<code>c1</code>的标签</li>
<li>找到本页面所有样式类中有<code>btn-default</code>的标签</li>
<li>找到本页面所有样式类中有<code>c1</code>的标签和所有<code>h2</code>标签</li>
<li>找到本页面所有样式类中有<code>c1</code>的标签和id是<code>p3</code>的标签</li>
<li>找到本页面所有样式类中有<code>c1</code>的标签和所有样式类中有<code>btn</code>的标签</li>
<p id="p2" class="divider"></p>
<li>找到本页面中<code>form</code>标签中的所有<code>input</code>标签</li>
<li>找到本页面中被包裹在<code>label</code>标签内的<code>input</code>标签</li>
<li>找到本页面中紧挨在<code>label</code>标签后面的<code>input</code>标签</li>
<li>找到本页面中id为<code>p2</code>的标签后面所有和它同级的<code>li</code>标签</li>
<p id="p3" class="divider"></p>
<li>找到id值为<code>f1</code>的标签内部的第一个input标签</li>
<li>找到id值为<code>my-checkbox</code>的标签内部最后一个input标签</li>
<li>找到id值为<code>my-checkbox</code>的标签内部没有被选中的那个input标签</li>
<li>找到所有含有<code>input</code>标签的<code>label</code>标签</li>
</ol>
</div>
</div>
</div>
<div class="my-dark my-padding">
<div class="container">
<div class="col-sm-8 my-center">
<p>写很少的代码，做很多的事。</p>
<h4>所以说</h4>
<p>学好jQuery真的很重要，学好jQuery真的很重要，学好jQuery真的很重要。</p>
</div>
</div>
</div>
<div class="footer">
<div class="row">
<div class="col-md-12 text-center">
<span class="my-white">©2020 Jason</span>
</div>
</div>
</div>
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>
</html>
答案：
$('#i1')
r.fn.init [div#i1.container]
$('h2')
r.fn.init [h2, prevObject: r.fn.init(1)]
$('input')
r.fn.init(9) [input#exampleInputEmail1.form-control, input#exampleInputPassword1.form-control, input#exampleInputFile, input, input, input, input, input#optionsRadios1, input#optionsRadios2, prevObject: r.fn.init(1)]
$('.c1')
r.fn.init(2) [h1.c1, h1.c1, prevObject: r.fn.init(1)]
$('.btn-default')
r.fn.init [button#btnSubmit.btn.btn-default, prevObject: r.fn.init(1)]
$('.c1,h2')
r.fn.init(3) [h1.c1, h1.c1, h2, prevObject: r.fn.init(1)]
$('.c1,#p3')
r.fn.init(3) [h1.c1, h1.c1, p#p3.divider, prevObject: r.fn.init(1)]
$('.c1,.btn')
r.fn.init(11) [h1.c1, h1.c1, a.btn.btn-primary.btn-lg, button.btn.btn-warning, button.btn.btn-danger, button.btn.btn-warning, button.btn.btn-danger, button.btn.btn-warning, button.btn.btn-danger, button#btnSubmit.btn.btn-default, a.btn.btn-success, prevObject: r.fn.init(1)]
$('form').find('input')
r.fn.init(3) [input#exampleInputEmail1.form-control, input#exampleInputPassword1.form-control, input#exampleInputFile, prevObject: r.fn.init(1)]
$('label input')
r.fn.init(6) [input, input, input, input, input#optionsRadios1, input#optionsRadios2, prevObject: r.fn.init(1)]
$('label+input')
r.fn.init(3) [input#exampleInputEmail1.form-control, input#exampleInputPassword1.form-control, input#exampleInputFile, prevObject: r.fn.init(1)]
$('#p2~li')
r.fn.init(8) [li, li, li, li, li, li, li, li, prevObject: r.fn.init(1)]
$('#f1 input:first')
r.fn.init [input#exampleInputEmail1.form-control, prevObject: r.fn.init(1)]
$('#my-checkbox input:last')
r.fn.init [input, prevObject: r.fn.init(1)]
$('#my-checkbox input[checked!="checked"]')
r.fn.init(3) [input, input, input, prevObject: r.fn.init(1)]0: input1: input2: inputlength: 3prevObject: r.fn.init [document]__proto__: Object(0)
$('label:has("input")')
r.fn.init(6) [label, label, label, label, label, label, prevObject: r.fn.init(1)]