1. 肯定句
助动词had+主动词的过去分词
对于规则动词，过去分词是通过在动词的基本形式后面加上“-ed”来形成的。
对于不规则动词，过去分词的形式不同。
I had eaten breakfast before I went to work.
我在上班前吃过早餐。
She had studied for three hours before taking the exam.
她在考试前学习了三个小时。
They had visited Paris several times before moving there.
他们在搬到巴黎之前已经去过好几次了。
2. 否定句
助动词had+not+主动词的过去分词
I had not seen that movie before last night.
昨晚之前我没有看过那部电影。
She had not finished her homework before going to bed.
她睡觉前还没有做完作业。
They had not traveled abroad before last year.
去年以前他们没有出过国。
3. 疑问句
把主语和助动词had倒置
Had you eaten breakfast before you went to work?
你上班前吃过早餐了吗？
Had she studied for three hours before taking the exam?
她在考试前学习了三个小时吗？
Had they visited Paris several times before moving there?
他们在搬去巴黎之前去过几次吗？
二、常用的时间表达
常与过去完成时连用的时间表达有：
After, Before, By the time, Once, When
1. after
用after来描述过去发生在另一个动作之后的动作。
After I had finished my homework, I went to bed.
我做完作业后就上床睡觉了。
She called me after she had arrived at the airport.
她到机场后给我打了电话。
2. Before
用“before”来描述发生在过去另一个动作之前的动作。
I had eaten breakfast before I went to work.
我在上班前吃过早餐。
They had left before I arrived.
在我到达之前，他们已经走了。
3. By the time
用by the time来描述在过去某个特定时间之前完成的动作。
By the time I got to the party, everyone had already left.
当我到达聚会时，每个人都已经离开了。
She had finished her work by the time her boss came in.
老板进来时，她已经完成了工作。
4. Once
用“once”来描述过去紧接着另一个动作发生的动作。例如:
Once I had finished my presentation, I felt relieved.
演讲一结束，我就松了一口气。
Once she had completed her studies, she got a job.
她一完成学业就找到了一份工作。
5. When
用“when”来描述与过去发生的另一个动作同时发生的动作。
I had just finished cooking when my friends arrived.
我刚做完饭，我的朋友们就来了。
They had already left when I got there.
我到那里时，他们已经走了。
过去完成时通常与一般过去时连用，以表示过去发生的事件的顺序。
I _______ (finish) my homework before I watched TV. They _______ (leave) by the time we arrived. She _______ (not see) that movie before. Had you _______ (eat) breakfast before you left? He _______ (already start) his project when we called.
Answers:
had finished had left had not (hadn’t) seen eaten had already started
参考来源：
https://www.engclub.in/p/past-perfect-tense.html
https://eslbuzz.com/past-perfect-tense/
