<div  class="clearfix">
<div class="pull-left">
<?php if (get_previous_post()) { previous_post_link('上一篇: %link');} else {echo "已经是最后文章";} ?>
</div>
<div class="pull-right">
<?php if (get_next_post()) { next_post_link('下一篇: %link');} else {echo "已经是最新文章";} ?>
</div>
</div>

类名为bootstrap类名

<div  class="clearfix"></div> 清除div里子元素的浮动

<div class="pull-right"></div>  div元素向左浮动

<div class="pull-left"></div>   div元素向右浮动