解放军文职考试：双重介词

　　所谓双重介词就是指由两个简单的介词重叠使用而构成的，如from behind, from among, since before, until after, except on等。如：

　　A man stepped out from behind the wall. 一个人从墙后走出来。

　　He cannot spare any time except on Sunday. 除星期日外，他抽不出时间。

　　I won’t go home until after the exam. 我要等考完后再回家。

　　He has known her since before the war. 自战前开始他就认识她。