概念：表示在过去某一时间或动作之前已经发生或完成了的动作，即“过去的过去（ past-in-the-past ）”。
构成：“助动词 had + 过去分词”，其中 had 通用于各种人称。
They had already had breakfast before they arrived at the hotel. 在到达旅馆之前，他们已经吃过了早饭。
She had finished writing the composition by 10：00 this morning. 今天早晨10点之前，她已经写完了作文。
When I woke up, it had stopped raining. 我醒来时，雨已经停了。（雨停发生在醒来之前，即“过去的过去”）
By the end of last year, he had worked in the factory for twenty years. 到去年年底为止，他已经在这个工厂工作了20年。（ 到去年年底为止已工作了 20 年，还有继续进行下去的可能）
（1）by + 过去的时间点，例如：
I had finished reading the novel by nine o'clock last night. 到昨天晚上九点钟为止，我已经读完了这本小说。
（2）by the end of + 过去的时间点，例如：
We had learned over two thousand English words by the end of last term. 到上学期末为止，我们已经学了两千多单词。
（3）before + 过去的时间点，例如：
They had planted six hundred trees before last Wednesday. 在上周三之前，他们已经植了六百棵树。
She said that she had seen the film before. 她说她之前看过这部电影。
When I got to the station, the train had already left. 当我到达车站的时候，火车已经离开了。
注意：before, after 引导的时间状语从句中，由于 before 和 after 本身已表达了动作的先后关系，若主、从句表示的动作紧密相连，则主、从句都用一般过去时。例如：
Where did you study before you came here? 在你来这里之前，你在哪里学习？
After he closed the door, he left the classroom. 他关上门后，离开了教室。
（3）表示意向的动词，如hope, wish, expect, think, intend, mean, suppose等，用过去完成时表示"原本…，未能…"，例如：
We had thought that you would come, but you didn't. 我原认为你会来的，但是你没有。
I met Wang Tao in the street yesterday. We hadn't seen each other since he went to Beijing. 昨天我在街上遇到了王涛。自从他去了北京我们一直还没有见过彼此。
They had arrived at the station by ten yesterday. 到昨天十点为止，他们已经到达了车站。
They arrived at the station at ten yesterday. 他们在昨天十点的时候到达车站。
She was very happy. Her whole family were pleased with her, too. She had just won the first in the composition competition. 她很高兴。她的全家对她也很满意。她刚刚在作文比赛中得了第一。
【典型考例】John and I____ friends for eight years. We first got to know each other at a Christmas party. But we_____ each other a couple of times before that.
A. had been; have met B. have been; have met C. had been; had met D. have been; had met
1. We _____________ (paint) the house before we ______________ (move) in.
2. That rich old man _____________ (make) a will before he _____________ (die).
3. They _____________ (study) the map of the country before they ________ (leave).
4. The robbers _____________ (run )away before the policemen _______ (arrive).
5. I __________ (turn) off all the lights before I ____________ (go) to bed.
6. Paul __________ (go) out with Jane after he __________ (make) a phone call.
7. Tom __________ (say) he ___________ (read) the book twice.
8. Our plan ____________ (fail ) because we _____________ (make) a bad mistake.
9. She told me she _________________(be) to Chongqing three times.
10.He said he _____________already_________(give) the book to the teacher.
11.When I ______________(get) at the station, the train ____________________(leave).
12.We _______________(learn) about 4000 English words by the end of last term.
13. I waited until he _______________(finish) his homework.
14. We were surprised at what she ________already ______(do)
1. I lost the book I________.
A．have bought B．bought C．had bought D．had been bought
2．The bus ______ when I arrived at the bus stop．
A．has gone B．went C．had gone D is going
3．Tom ＿＿＿＿ of visiting his grandmother，but the bad weather made him change his mind．
A．has thought B．thought C．had thought D．had been thought
4．—Did you meet Tom at the airport？
—No，he ＿＿＿ by the time I ＿＿＿ there．
A．has left；got B．had left；arrived C．left；arrived D．left；had got
5．—Why didn't Tom attend the meeting yesterday？
—He ＿＿＿＿ Beijing．
A．has gone to B．had gone to C．went to D．had been to
6．In this experiment, they are woken up several times during the night, and asked to report what they＿＿＿＿.
A. had just been dreaming B. are just dreaming
C. have just been dreaming D. had just dreamt
7．Finally Mary was admitted by Beijing University，for which she＿＿＿ five times．
A．had tried B．was trying C．has tried D.tried
8．—I have bought you the books you want．
—Oh，good，I was afraid you _______．
A．forgot B．forget C．had forgotten D．have forgotten
9. We ____five English songs by the end of last term.
A had learned B learned C have learned D will have learned
1.He has collected over 300 Chinese stamps. Mike told us.（合并为一句）
Mike told us that he _______ ______ over 300 Chinese stamps.
2.What he did . We didn’t know （合并为一句）
We didn’t know what he _______ ______.
3.The plane set off. By the time we got to the airport. （合并为一句）
By the time we _____ to the airport, the plane ______ ______ off.
4.We didn’t know. He will come. （合并为一句）
We didn’t know he ______ ______.
It would be great if you can tell me _______________________________