过去完成时（Past perfect tense）
过去完成时由had + 过去分词构成
I had worked as a worker for five years before I became a teacher.
By the end of last year, I had already learnt 5,000 English words.
2)动词的过去完成时可以用于表示一个本来打算做而没有做的事，常用的动词有：intend, hope, want, mean, suppose, expect, think等。
I had intended to meet you at the airport, but someone came to see me just when I was about to leave.
I had wanted to lend you some money, but you didn't ask.
3)在有hardly…when, no sooner…than等副词的句中，也使用过去完成时，表示“刚刚…就”，“一…就”。
Hardly had I arrived home when it began to rain.
No sooner had they left the building than a bomb exploded.
4)过去完成时还用于下面句型中 It was the first time that…。
It was the first time that I'd seen such a beautiful place.
It was the first Hollywood film I had ever seen in America.
When I got to the airport, the plane had already taken off.
The plane took off five minutes ago.
I went to bed after I had finished reading the interesting novel.
He told me that Sony Corporation had bought Columbia Pictures for$5 billion.