We use the past perfect tense to talk about an action that happened before another action in the past. The earlier action is expressed in the past perfect tense and the later action is expressed in the simple past tense.
1.过去完成时常与 before 等词构成的短语连用。如： 过去完成时常与by, 等词构成的短语连用。 过去完成时常与 1) 到上学期末为止我们已学了三千多个英语单词了。 到上学期末为止我们已学了三千多个英语单词了。
We had learned over 3,000 English words by the end of last term.
4.过去完成时可用在宾语从句中或通过上下文表示。如： 4.过去完成时可用在宾语从句中或通过上下文表示。 过去完成时可用在宾语从句中或通过上下文表示
1)他说他已买了一辆新自行车。 1)他说他已买了一辆新自行车。 他说他已买了一辆新自行车 He said he had bought a new bike. 2) 我同桌告诉我她去过北京两次了。 我同桌告诉我她去过北京两次了。 My partener told me she had been to Beijing trwice.
1)做完作业后，他上床睡觉了。 做完作业后，他上床睡觉了。 做完作业后 After he had finished his homework, he went to bed. 2)当他关了灯后 就锁上门回家了。 当他关了灯后, 当他关了灯后 就锁上门回家了。 When he had turned off the light, he locked the door and went home.
