42.A. He became an English teacher 15 years ago.

　 B. He ________ ____________ an English __________ 15 years ago.

C. He __________ __________ English for 15 years.

　D. It ________ ____________ 15 years ____________ he started teaching English 15 years ago.

41.A. I closed the window two minutes ago.

B. The window __________ ___________ ____________ for two minutes.

40.A. It’s about ten minutes since he left the room.

　 B. He ________ the room ten minutes __________.

　　 C. He ________ __________ ___________ ___________ the room for about ten minutes.

39.A. His uncle bought the new house two and a half years ago.

　 B. His uncle ___________ __________ the new house for ________ ________ and ______ _________.

e.g.　　 I borrowed this book from the school library three weeks ago.

　　　 = I have kept this library book for three weeks.

　 此类题目既要要求对一些动作动词(常是瞬间动词)相关的状态动词(常是非延续动词)很熟悉，还要注意时态的变化，通常是一般现在时变为现在完成时。特别注意瞬间动词不能与表示一段的时间状语联用；有些句子在变化时主语要作一定的调整。

Exercises:

38.A. The young man has been in the army for four years.

　 B. The young man ___________ the army four years _________.

C. __________ two years ___________ the young man ________ the army .

37.A. A large number of people speak English in the world.

　 　B. English __________ ____________ ________ many people in the world.

36.A. People grow rice in southern China.

　 B. Rice _______ ___________ in southern China.

35.A. People built this bridge 1500 years ago.

　 　B. This bridge _________ ___________ 1500 years ago.

34.A. We must look after old people well.

　 　B. Old people ___________ _________ __________ ________ well.

e.g. Father made his children work hard every day.

= The children were made to work hard every day.

此类题目要注意时态的一致，主语和谓语在数上的一致，短语的完整性。特别注意有些主动语态中生的省to 不定时改为被动语态后要还原不定时符号to.

Exercises：

33.A. The student were asked to finished their homework in class by the teacher.

　 　B. The teacher __________ __________ ________ finish their homework in class.