<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" >
中间
</div>
<div style="background-color:red;" class="col-sm-12 col-md-3" >
右边
</div>
</section>