复制
1<style type="text/css">
2     #parent p { background-color: red;  }
3      div .a.b.c.d.e.f.g.h.i.j.k p{ background-color: green;  
4</style>
5......
6<div id="parent">
7     <div class="a b c d e f g h i j k">
8         <p>xxxx</p>
9     </div>
10</div>
11