<button type="button" class="btn btn-default">
 <span class="glyphicon glyphicon-sort-by-attributes"></span>
</button>

<div class="dropdown">
 <button type="button" class="btn dropdown-toggle" id="dropdownMenu1" 
 data-toggle="dropdown">
 主题
 <span class="caret"></span>
 </button>
 <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
 <li role="presentation" class="dropdown-header">下拉菜单标题</li>
 <li role="presentation">
 <a role="menuitem" tabindex="-1" href="#">选项1</a>
 </li>
 <li role="presentation">
 <a role="menuitem" tabindex="-1" href="#">选项2</a>
 </li>
 <li role="presentation"> 
 <a role="menuitem" tabindex="-1" href="#">选项3</a>
 </li>
 <li role="presentation" class="divider"></li><!--分割线-->
 <li role="presentation">
 <a role="menuitem" tabindex="-1" href="#">分离的链接</a>
 </li>
 </ul>
</div>

<div class="btn-toolbar" role="toolbar"><!--用来嵌套btn-group-->
 <div class="btn-group btn-group-lg">
 <!--btn-group-lg用来控制按钮组的大小,bt-group-vertical是垂直的按钮组,bt-group也可以嵌套bt-group-->
 <button type="button" class="btn btn-default">Button 1</button>
 <button type="button" class="btn btn-default">Button 2</button>
 <button type="button" class="btn btn-default">Button 3</button>
 </div>
 <div class="btn-group btn-group-sm">
 <button type="button" class="btn btn-default">Button 4</button>
 <button type="button" class="btn btn-default">Button 5</button>
 <button type="button" class="btn btn-default">Button 6</button>
 </div>
 <div class="btn-group btn-group-xs">
 <button type="button" class="btn btn-default">Button 7</button>
 <button type="button" class="btn btn-default">Button 8</button>
 <button type="button" class="btn btn-default">Button 9</button>
 </div>
</div>

 <div class="btn-group"><!--加类.dropup可以变成按钮上拉菜单-->
 <button type="button" class="btn btn-default dropdown-toggle" 
 data-toggle="dropdown"> <!-- 加类.btn-xs之类的东西改变按钮大小-->
 默认 <span class="caret"></span>
 </button>
 <ul class="dropdown-menu" role="menu">
 <li><a href="#">功能</a></li>
 <li><a href="#">另一个功能</a></li>
 <li><a href="#">其他</a></li>
 <li class="divider"></li><!--分割线-->
 <li><a href="#">分离的链接</a></li>
 </ul>
 </div>

<form class="bs-example bs-example-form" role="form">
 <div class="input-group input-group-lg"><!--input-group-lg调整输入框组大小-->
 <input type="text" class="form-control">
 <span class="input-group-addon">.00</span>
 </div>
 <br>
 <div class="input-group">
 <span class="input-group-addon">
 <input type="checkbox"><!--复选框和单选框都能应用于输入框组-->
 </span>
 <input type="text" class="form-control">
 </div>
 <br>
 <div class="input-group">
 <input type="text" class="form-control">
 <span class="input-group-btn"><!--按钮也能应用于输入框组请注意这里的类变为了input-group-btn，甚至可以加上前面的按钮下拉菜单-->
 <button class="btn btn-default" type="button">
 Go!
 </button>
 </span>
 </div>
 </form>