img-rounded：   圆角图片
img-circle：    圆形图片
img-thumbnail： 缩略图片

<span class="glyphicon glyphicon-ok"></span>

<table class="table"></table>

.active        鼠标悬停在行或单元格上时所设置的颜色.success    标识成功或积极的动作.info        标识普通的提示信息或动作.warning    标识警告或需要用户注意.danger        标识危险或潜在的带来负面影响的动作

<div class="table-responsive">
      <table class="table">
     ...
      </table>
</div>

<form role="form">告诉辅助设备（如屏幕阅读器）这个元素所扮演的角色是个表单</form><form role="button">告诉设备，这是个按钮，可以点击。本质上是增强语义性，增强组件的可访问性、可用性</form>

<form>
      <div class="form-group">
            <label for="exampleInputEmail1">Email address</label>
             <input type="email" class="form-control" id="exampleInputEmail1" placeholder="Email">
       </div>
       <div class="form-group">
             <label for="exampleInputPassword1">Password</label>
             <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
        </div>
       <div class="form-group">
          <label for="exampleInputFile">File input</label>
             <input type="file" id="exampleInputFile">
           <p class="help-block">Example block-level help text here.</p>
     </div>
       <div class="checkbox">
             <label>
               <input type="checkbox"> Check me out
             </label>
      </div>
       <button type="submit" class="btn btn-default">Submit</button>
</form>

<form class="form-inline">
      <div class="form-group">
            <label for="exampleInputName2">Name</label>
            <input type="text" class="form-control" id="exampleInputName2" placeholder="Jane Doe">
      </div>
      <div class="form-group">
            <label for="exampleInputEmail2">Email</label>
            <input type="email" class="form-control" id="exampleInputEmail2" placeholder="jane.doe@example.com">
      </div>
     <button type="submit" class="btn btn-default">Send invitation</button>
</form>

<div class="checkbox">      <label>          <input type="checkbox" value="">
        Option one is this and that—be sure to include why it&#39;s great       </label></div>
<div class="checkbox disabled">      <label><input type="checkbox" value="" disabled>
            Option two is disabled      </label></div>

<div class="radio">
      <label>
            <input type="radio" name="optionsRadios" id="optionsRadios2" value="option2">
        Option two can be something else and selecting it will deselect option one
      </label>
</div>
<div class="radio disabled">
      <label>
            <input type="radio" name="optionsRadios" id="optionsRadios3" value="option3" disabled>
            Option three is disabled
      </label>
</div>