过去完成时表示到过去某一时间已完成的动作或状态。
过去完成时
1.动词形式
2.过去完成时用法
（1）表示到过去某一时间已完成或者结束的动作或状态。过去的某一时间通常是由by引起的时间状语。例如：
By Saturday night we had got everything ready for the part.
到星期六晚上我们已为聚会作好了一切准备。
They had arrived home by 5 p.m.
到下午五点他们已经回到家。
We had finished the job by Firday.
到星期王我们已经完成这项工作。
It is two days since he left for America.
他去美国两天了。
过去某一时间也可以通过时间状语从句表示：
He had already left when I got there.
我到那儿时他已经离开了。
We had studied a little Japanese before we came to Japan.
我们到日本前学过一点日语。
有时过去的时间也可以通过上下文情景来体现。比如：
I met Mary in the street one morning.She had changed greatly.
一天早晨我在街上遇见玛丽。她变化很大。
I didn't want to see the play because I had already seen it.
我不想看那部戏剧，因为我已经看过了。
When I got to George's office, he wasn't there. I was told that he had gone home.
我到乔治办公室时,他不在.有人告诉我他回家了。
2.过去完成时用法
（2）表示持续到过去某一时间动作或状态。例如：
He had worked in the store for five years before he moved here.
我搬迁到这里来以前，在那家商店工作了五年。
句子成分分析：
本句He是主语，had worked是谓语动词(had 过去分词worked构成过去完成时形式), in the store是地点状语,for five years是时间状语(for 一段时间构成),before引导状语从句,he是从句的主语,moved是谓语动词(过去式),here是状语。
She told me that she had been an air hostess for quite a few years.
她告诉我她当空中乘务员好几年了。
（3）表示运去某一时间为止发生的动作次数的总和或具有的经历。比如：
She said that she had been to Shanghai.
她说她已来过上海。
句子成分分析：
She是主语，said是谓语动词（过去式），that引导宾语从句,she是从句的主语，had been to Shanghai是状态型谓语（had been表示过去完成时）。
By the end of the year we had planted many trees in our neighbourhood.
到年底我们在我们街坊种了许多树。
By the end of last term we had read ten short stories.
到上学期末，我们已读了十篇短篇小说。
3. 过去完成时与过去一般时的区别
过去完成时强调的是过某一时间或者另一动作前已完成的动作，因此一般须有一个过去的时间作参照标准或与另一过去的动作发生有先后关系。过去完成时也称"过去的过去"，而一般过去时仅表示动作或者状态在过去某时间发生，所以不能认为凡是过去发生的动作或状态都用过去完成时。例如：
He had fallen ill when he finished the job.
当他完成这项工作时已经病倒
句子结构分析：He是主语，had fallen ill是系表型谓语（had fallen是过去完成时形式），when引导时间状语从句，he是主语，finished是谓语（过去式），the job是宾语。
He fell ill three days after he returned from his trip.
他旅游回来三天后病倒了。
He had taught English for twenty years when here tired.
当他退休时，他已教英语二十年了。
He had taught English for twenty years after he graduated from college.
他大学毕业后教过二十年英语。
