(九)过去完成时

　　过去完成时表示在过去某个时间或动作以前已经发生的动作或情况，简单地说就是表示"过去的过去"。

　　过去完成时的谓语形式：had +过去分词。

　　When we got to the theatre, the play had already started.

　　He suddenly remembered that he hadn't locked the door when he left.

　　By the end of that year we had trained more than 1,000 employees.

　　They had been married many years before a child was born to them.

　　No sooner had we left the school than it began to rain.(no sooner…than= as soon as 一……就……，no sooner开头的句子要倒装)

　　(十)过去完成进行时

　　表示动作在过去某一时间之前开始，一直延续到这一过去时间。这个时态必须以一过去的时间为前提。

　　过去完成进行时的谓语形式：had been+现在分词

　　I had been looking for it four days before I found it.

　　The telephone had been ringing for three minutes before it was answered.

　　It had been raining for two days. The fields were all under water.

　　At last we got the letter we had been expecting.

　　1. "How long had you been waiting before Mr. Winter finally arrived?"

　　"Well, he came at three o'clock, and I _______ the day before."

　　A. had waited after B. had been waiting since

　　C. was waiting from D. had been waiting for

　　等某人 wait for sb.

　　for接一段延续的时间，since接过去时间状语或过去时句子。

　　答案 B