您可以同时使用 pull-left & pull-right 或 col-xs-6 ，具体取决于您要实现的目标.

You can use both pull-left & pull-right or col-xs-6, depending upon what exactly you want to achieve.

下面是jsfiddle链接后面的代码，显示了已完成的两件事:

Here's the code followed by jsfiddle link showing both things done:

    body {
      background-color: black;
    }
    #test-1 {
      background-color: white;
      height: 200px;
      width: 200px;
    }
    #test-2 {
      background-image: url("http://www.rd.com/wp-content/uploads/sites/2/2016/04/01-cat-wants-to-tell-you-laptop.jpg");
      background-size: cover;
      background-repeat: no-repeat;
      height: 200px;
      width: 200px;
    }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

    <!-- Latest compiled and minified CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

    <!-- Optional theme -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css" integrity="sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp" crossorigin="anonymous">

    <!-- Latest compiled and minified JavaScript -->
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>

    <div class="row-fluid">
          <div id="test-1" class="span6 pull-left"></div>
          <div id="test-2" class="span6 pull-right"></div>
        </div>
        
        <div class="clearfix"></div>
        
        <div class="row-fluid">
          <div id="test-1" class="span6 col-xs-6"></div>
          <div id="test-2" class="span6 col-xs-6"></div>
        </div>

Jsfiddle链接: https://jsfiddle.net/jLfcpssz/

Jsfiddle link: https://jsfiddle.net/jLfcpssz/