引导媒体不显示图像src但网格缩略图是

Question

我错过了有关自举媒体的特别之处吗？ 以下媒体代码没有给我一张图片：

<div class="container">
<div class="media">
      <a class="media-left media-bottom" href="#">
        <img class="pull-left" src="air.jpeg">
      </a>
      <div class="media-body">
        <h4 class="media-heading">Bottom aligned media</h4>
        <p>Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.</p>
        <p>Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.</p>
      </div>
    </div>
</div>

但是同一图像的网格代码正在运行：

div class="row">
  <div class="col-md-3">
    <div class="thumbnail">
      <img src="air.jpeg" alt="air feed">
      <div class="caption">
        <h3>Classify millions of tweets on important legislation </h3>
        <p>Input the legislation name or bill number and measure how the internet views it.</p>
        <p><a href="#" class="btn btn-primary" role="button">More</a> <a href="#" class="btn btn-default" role="button">Data</a></p>
      </div>
    </div>
  </div>

没有意义。