在学习英语的过程中，掌握时态是非常重要的。其中，过去完成时是表达过去某个时间之前已经发生或完成的动作或状态的一种重要语法结构。为了帮助大家更好地理解和运用过去完成时，下面为大家准备了20道练习题，并附有详细答案解析。
一、单项选择题
1. By the time I got to the station, the train ________ already ________.
A. has; left
B. had; left
C. was; leaving
D. would; leave
解析：正确答案为B。由“by the time”引导的时间状语从句表明动作发生在过去的过去，因此需要用过去完成时。
2. She ________ her homework before she went out to play.
A. finished
B. finishes
C. had finished
D. was finishing
解析：正确答案为C。“before”引导的时间状语从句中，“went out to play”表示过去发生的动作，“finished”则发生在“went out”的之前，故需使用过去完成时。
3. When he arrived at the office, the meeting ________ for 15 minutes.
A. had started
B. had been on
C. had begun
D. had been held
解析：正确答案为B。“for+一段时间”常与延续性动词连用，这里“be on”表示会议正在进行。
4. By the end of last year, they ________ more than 100 books.
A. read
B. were reading
C. had read
D. would read
解析：正确答案为C。根据“by the end of last year”，强调的是到过去某一时间点之前已经完成的动作，因此要用过去完成时。
5. The teacher said that the students ________ their compositions by 5 o'clock.
A. have finished
B. will finish
C. would finish
D. had finished
解析：正确答案为D。这里的“said”表明是在过去说话，而“finish”这个动作发生在“said”之前，所以用过去完成时。
……
二、完形填空
6. It was raining heavily when we arrived at the airport. We found that our flight ________.
7. By the time the doctor came, the patient ________.
8. He told me that he ________ his work before he went home.
9. When I saw him yesterday, he ________ for the bus.
10. They ________ the project by the time you visited them last month.
……
以上只是部分题目展示，完整版包含20道题及详细解答，请根据需要下载或打印进行练习。通过反复练习，相信大家可以更加熟练地掌握过去完成时的用法。
