一. Tenses and voices
A. 现在完成时: 1)表示过去某时发生的行为对主语目前产生的影响。即用过去发生的某个行为来说明现在的某种情况。往往含有“已经……”, “已经……了”的意思。
Eg.Don’t think any more about it. I have decided not to help you.
I have experienced that before, so I know how to deal with it.
2) 到目前为止已发生的。与so far, up till now, in the past/ last …….days/ years, today, this month/ year 等 “包括现在在内的时间状语”连用。
My brother is an actor. He has appeared in several films so far.
Great changes have taken place in this area in the recent years.
3)表示过去开始的动作或状态延续到现在。与for…/ since 连用。
He has worked in the south for ten years/ since ten years ago.
Compare(1):完成进行时表示过去开始的动作一直在进行，直至现在。
He has been working on this project since last month.
(2) 过去时态:指发生在过去某段时间内的事。
He once worked in the south for ten years (现在不在南方)
(3) 过去完成时态:指发生在过去某个时间以前的动作或状态。常与by/ by the end of..(到了……的时候”连用。例如：
1)By the time we got to the theatre, they had sold all the tickets.
2)How many words had you leaned by the end of last year?
Practice:
1.It is reported that the president once______ in the Viet Nam’s war for three years from 1966-1970. A. served B. had served C. has served D. was serving
2. ---No one answered when I called at 6 yesterday.
---I ________ to rock music and was absorbed in it.
A listened B was listening C. has listened D. had listened
3.I wasn’t paying attention to what he was talking about, so I am afraid I ___ his speech very well.
A. had not understood B. has not understood C. did not understand D. don’t understand
4. I _____ good at table tennis, but I haven’t played it for ages.
A. am B. was C. has been D. used to be
5. I _________ where she gets her money all these days.
A. am often wondering B. often wondered C. had often wondered D.have often wondered
6. ---Tell me what _______ while I was absent.
---A thief tried to break into the house when I _______ in your house.
A. happened/ stayed B. was happening/ was staying
C. happened/ was staying D. was happening/ stayed
7. ---You are always watching TV.
---Only on Sundays. And nobody ______ it but you.
A. knows B. has known C. knew D. is knowing
8. When the old man ______ to walk back to his house ,the sun _____ itself behind the mountain.
A.started ;had already hidden B.had started ;had already hidden
C.had started ;was hiding D.was starting; hid
9. Years ago we didn't know this, but recent science ______ that people who don't sleep well soon get ill. A. showed B. has shown C. will show D. is showing
10. It ______ for weeks before the first cold wave struck the area.
A. rained B. was raining C. has rained D. had been raining
Keys:1)a 2)b. 3)c 4)a 5) 过去到现在d 6) c 7)a(经常性) 8)a 9) b 与现在有联系 10)d

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