小學(xué)英語語法知識點：過去完成時

　　1）概念：表示過去的過去

　　--那時以前--那時--現(xiàn)在--

　　其構(gòu)成是had +過去分詞構(gòu)成。

　　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 when he arrived at the party.

　　典型例題

　　The students ___ busily when Miss Brown went to get a book she ___ in the office.

　　A. had written， left　B，were writing， has left　 C. had written， had left　D. were writing， had left

　　答案D. “把書忘在辦公室”發(fā)生在“去取書”這一過去的動作之前，因此“忘了書”這一動作發(fā)生在過去的過去，用過去完成時。句中when表示的是時間的一點，表示在“同學(xué)們正忙于……”這一背景下，when所引導(dǎo)的動作發(fā)生。因此前一句應(yīng)用過去進行時。

　　注意：had no … when  還沒等…… 就……

　　had no sooner… than  剛…… 就……

　　He had no sooner bought the car than he sold it.