大学英语：过去完成时

　　1.概念
　　（1）表示过去某时之前业已发生的动作，发生在前面的用过去完成时，发生在后面的用一般过去时。
　　（2）在过去某时之前，动作已经完成或结束。
　　（3）造成的是对过去的影响或结果，与现在没有关系。
　　（4）过去完成时一般都有过去时相衬托。
　　2.基本结构
　　S+had+动词的过分（P.P.）
　　When I got to the station the train had left.
　　I had been at the bus stop for over one hour when a bus finally came.
　　I had wanted to attend the meeting, but I fell ill.(未完成)
　　3.难点
　　（1）当几个动作用and， then, but等连词时，因为有动作先后顺序，须用一般过去时。
　　He stood up, took his coat and went out.
　　(2)如果有after, before, as soon as等连用，且清楚有动作先后，从句一般用过去时或过去完成时。
　　I told them the news after you (had) left
　　As soon as I (had) put the phone down it rang again.
　　They had already sold it when I asked the price of that car.
　　(3)注意固定搭配来自www.Examw.com
　　hardly...when..., no sooner...than, scarcely...when etc.
　　He had hardly arrived when it began to snow.
　　We’d scarcely arrived when she started crying.
　　(4)用于hope, intend, mean, think等词的过去完成时，表示未实现的愿望。
　　We had thought to return early but they wouldn’t let us go.
　　(5)用于expect, hope, want, think等词的过去时，表示“比……”。
　　It was easier than I had thought.
　　We arrived earlier than we had expected.
　　The place wasn’t as clean as we had wanted it to be.