過去完成時
　　
1） 概念：表示過去的過去
其構成是had +過去分詞構成。
那時以前　 那時　現(xiàn)在
　　
2） 用法
a.　在told, said, knew, heard, thought等動詞后的賓語從句。
She said (that) she had never been to Paris.
b. 狀語從句
在過去不同時間發(fā)生的兩個動作中，發(fā)生在先，用過去完成時；發(fā)生在后，用一般過去時。
When the police arrived, the thieves had run away.
c. 表示意向的動詞，如hope, wish, expect, think, intend, mean, suppose等，用過去完成時表示"原本…，未能…"
We had hoped that you would come, but you didn't.
　　
3)　過去完成時的時間狀語before, by, until , when, after, once, as soon as。
He said that he had learned some English before.
By the time he was twelve, Edison had began to make a living by himself.
Tom was disappointed that most of the guests had left.