YII2 怎样使用bootstrap的流式布局 [ 2.0 版本 ]

各位好：
请问在YII2.0中怎样可以使用流式布局呀，我如下部分所写：

<?php $this->beginBody() ?>
    <div class="container-fluid">
        <div class="row-fluid">
            <div class="span4">
                <h1>qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq</h1>
            </div>
            <div class="span8">
                <h1>aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaqqqqqqqqqqqqqqqqq</h1>
            </div>
        </div>
</div>

<?php $this->endBody() ?>

没有反应呀，为什么呢？