在学习英语的过程中，掌握各种时态的使用是非常重要的。今天，我们来探讨一下英语中的过去完成时，并通过一些练习题来加深理解。

过去完成时的基本结构

过去完成时主要用于描述在过去某个时间点之前已经完成的动作或状态。其基本结构为：

主语 + had + 过去分词

例如：

- She had finished her homework before dinner.

- They had already left when we arrived.

练习题

1. 单项选择题

1. By the time he got to the station, the train ________.

A. has left

B. was leaving

C. had left

2. When I arrived at the office, the meeting ________ for ten minutes.

A. had started

B. had been on

C. was on

3. By the end of last year, she ________ more than 50 books.

A. has read

B. had read

C. was reading

答案

1. C. had left

2. B. had been on

3. B. had read

小结

通过以上练习题，我们可以看到过去完成时主要用来表达在过去某一时间点之前已经完成的动作。希望这些题目能帮助大家更好地理解和运用过去完成时。

如果你还有其他疑问，欢迎继续交流！