SOURCE

<section class="row">
  <div style="background-color:yellow;" class="col-sm-3 col-md-3 col-xs-offset-3">
    左边
    <section class="row">
      <div class="col-xs-6">
        1
      </div>
      <div class="col-xs-6">
        2
      </div>
    </section>
  </div>
  <div style="background-color:orange;" class="col-sm-9  col-md-6 ">
    中
  </div>
  <div style="background-color:red;" class="col-sm-12  col-md-3">
    右边
  </div>
</section>
<section>
  <div class="container">
    <h1>
      Hello, world!
    </h1>
    <div class="row">
      <p>
        排序前
      </p>
      <div class="col-md-4" style="background-color: #dedef8;
      box-shadow: inset 1px -1px 1px #444, inset -1px 1px 1px #444;">
        我在左边
      </div>
      <div class="col-md-8" style="background-color: #dedef8;
      box-shadow: inset 1px -1px 1px #444, inset -1px 1px 1px #444;">
        我在右边
      </div>
    </div>
    <br>
    <div class="row">
      <p>
        排序后
      </p>
      <div class="col-md-4 col-md-push-8" style="background-color: #dedef8;
      box-shadow: inset 1px -1px 1px #444, 
      inset -1px 1px 1px #444;">
        我在左边
      </div>
      <div class="col-md-8 col-md-pull-4" style="background-color: #dedef8;
      box-shadow: inset 1px -1px 1px #444, 
      inset -1px 1px 1px #444;">
        我在右边
      </div></section>