标志：had + 动词的过去分词

1. 表示在过去的某个时间或动作以前已经发生的动作或已经存在的状态。如：

By the end of last week he had finished the work.

He had left when I arrived.

2.  表示从过去某一时间开始，一直延续到过去另一时间的动作或状态。如：

We had not seen each other since I left Beijing.

The film had been on for 5 minutes when I got to the cinema.

3. 某些表意向的动词（如intend, think, plan, expect, hope等）的过去完成时表示主语未曾实现的愿望、希望、打算。如：

I had intended to visit you last night, but someone called and I couldn’t get away.

We had hoped that you would come, but you didn’t.

4. （虚拟语气）在条件状体从句或wish / would rather等后面的从句中，使用过去完成时表示与过去事实相反的主观愿望。如：

The party wouldn’t have been so perfect if you hadn’t come.

I wish I had gone with you to the concert that day.

5.  过去完成时与一般过去时

1) 基本区别：过去完成时表示以过去某时间为起点以前所发生的动作或存在的状态，即过去完成时强调“过去的过去”，而一般过去时只表示以现在时间为起点以前所发生的事情或存在的状态。如：

He studied there two years ago.他两年前在那儿学习（离现在两年）

He said he had studied there two years before.他说他两年前在那儿学习过。（离他说话时两年）

2) 特别注意：两个动作如果按顺序发生，又不强调先后，或者用then, and, but等连词连接时，多用一般过去时。如：

When she saw the mouse, she screamed.

My aunt gave me a hat and I lost it.