如果在一个 `.row` 内包含的列（column）大于12个，包含多余列（column）的元素将作为一个整体单元被另起一行排列。  ~~~html <div class="row"> <div class="col-xs-9">.col-xs-9</div> <div class="col-xs-4">.col-xs-4<br>Since 9 + 4 = 13 &gt; 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.</div> <div class="col-xs-6">.col-xs-6<br>Subsequent columns continue along the new line.</div> </div> ~~~