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Unit 1 Past and present
Grammar
知识点：
一、基本概念
现在完成时态表示过去发生的动作对现在的影响或有无某方面的经历。
时态构成：have/has + 动词过去分词
现在完成时态是很难掌握的一种时态，因为它并不是表示发生在某一时间的事情，而是既涉及过去，又联系现在的一种时态。
二、动词过去分词变化
规则动词过去分词的变化
①一般情况→词尾+ed
②以不发音字母e结尾→词尾+d
③以“辅音字母+y”结尾→变y为i，再加-ed
④以重读闭音节结尾，且末尾只有一个辅音字母→双写词尾+ed
注：还有许多动词的过去式和过去分词的变化是不规则的。(参考不规则动词表)
三、现在完成时的句型结构
1.肯定式
主语 + 助动词(have/has)+过去分词+其他
2.否定式
主语 + has/have + not+过去分词+其他
3. 疑问式
Has/Have + 主语+过去分词+其他+“？”
肯定回答常用：Yes, 主语+has/have，有时也用：Yes, already
否定回答常用：No, 主语+hasn’t/haven’t，有时也用“No, not yet”等形式。
四、现在完成时的用法
A. 现在完成时表结果：表示过去发生或已经完成的某一动作对现在造成的影响和结果，可以和already, yet, just，recently等连用。
B. 现在完成时表继续：表示过去已经开始，持续到现在，还可能继续下去的动作或状态，可以和表示从过去某一时刻延续到现在的一段时间的状语连用。如：since+过去的时间点, for+时间段，so far，up to now, over the past few years等；
C. 现在完成时表经验：表示从过去到现在之间曾经经历过的事情，常和never, ever, once, three times, before等连用。
注意：
1)already和yet
already (“已经”，用在肯定句)
yet (“已经”,用在疑问句;“还”用在否定句)
2)for和since：
since短语或从句表示过去的动作延续至今，since+时间点。
since+一般过去时 如：She has worked here since she came to Suqian.
since+过去的时间点 如：She has worked here since 1980.
since+一段时间+ago 如：She has worked here since two years ago.
for短语表示动作延续多长时间，
for+时间段 如：She has worked here for two years.
since＋一段时间＋ago＝for＋时间段;
3)ever和never
ever (“曾经”，用在疑问句中)
never (“从未” 表示否定)
同步练习
一、根据句意及中、英文提示或首字母完成单词
1. _______(最近), citizens in Luhe have got the chance to experience a self-service store.
2. I have been to Beijing many times in the_______(过去的) few years. It’s an old city.
3. Oh, my God! You haven’t finished your homework_______(还，仍).
4. -Have you e_______eaten chocolate
-No.
5. My mother has n_______been to the Great Wall. We will go there this summer.
答案：1. Recently 2. past 3. yet 4. ever 5. never
二、用所给单词或短语的适当形式填空
1. Tom_______(teach) in this school since 1992.
2. I am going to talk about some_______(change) in my daily life.
3. -_______you_______(receive) any letters from him recently
-Not yet.
4. -How many times_______you_______(read) this book by Jim
-Never.
5. Uncle Chen_______(repair) more than five bicycles since last Friday.
6. -Are you thirsty
-No. I_______just_______(have) some orange.
7. So far, my little brother_______(feed) all the animals on the farm.
8. -Turn off the TV, dear! The baby is sleeping.
-There is no need. He_______(wake) up.
9. I_______(lend) her some CDs three days ago, but she_______(not give) them back to me yet.
10. -Do you still play basketball
-Oh, no. I_______(not play) it in the past two years.
答案：1. has taught 2. changes 3. Have, received 4. have, read 5. has repaired
6. have, had 7. has fed 8. has woken 9. lent, hasn’t given 10. haven’t played
三、单项选择
( ) 1. Copying others’ homework is a bad learning habit. _______, it is never too late for you to get out of it.
A. Instead B. Finally C. Anyway D. Similarly
( ) 2. -Ms Griffin, what should we do_______stupid mistakes in the coming exams
-Be more careful.
A. avoid make B. avoiding making C. avoid making D. to avoid making
( ) 3. -The air is very fresh in our city. There is less_______than before.
-Yes. The government has taken action to protect the environment.
A. wood B. pollution C. noise D. water
( ) 4. -Where do you live
-I live near the supermarket in the_______part of town_______my family.
A. north, with B. northern, with C. north, and D. northern, and
( ) 5. -It has been much easier for me to go to work_______shared bikes appeared.
-But they also caused plenty of problems.
since B. before C. unless D. though
答案：1-5 CDBBA
四、按要求完成句子
1. I bought a new iPhone 7 Plus just now.(用just改写句子)
I_______ _______bought a new iPhone 7Plus.
2. I’ve worked in the shopping mall since I came to this city.(对画线部分提问)
_______ _______ _______you_______in the shopping mall
3. I have learned English since two years ago.(改为同义句)
I have learned English_______ _______ _______.
4. Our town has changed a lot over the years.(改为同义句)
There_______ _______many_______in our town over the years.
5. Li Lei often played football in the past, but now he doesn’t.(改为同义句)
Li Lei_______ _______ _______football, but now he doesn’t.
答案：1. have just 2. How long have, worked 3. for two years
4. have been, changes 5. used to play
五、根据短文内容及首字母提示，填写所缺单词
In some ways, young people between 12 and 19 now are much the same as young people used to be twenty years ago. The pictures of their favourite stars on bedroom walls look the same; only the names are d___1____.
In some other ways, teenagers are quite different. Young people don’t get ill e___2____now. And they have more chances to learn a___3____the world. Their minds seem to be more open. However, there is a new problem-the n___4____of televisions and computers in teenagers’ bedrooms is increasing. Many parents are w___5____about that. Sarah Kennedy has two sons. One is 14 and the other one is 17. Sarah Kennedy knows that they spend a lot of time in their rooms p___6____computer games. And she thinks that this is really a bad thing. “They always tell me that they’re doing their homework, b___7____I know that they aren’t. When I was their age, I really e____8___playing outside with my friends, but Steve and Robert only seem i___9____in new CDs or what is on television. I r___10____don’t know what to do about that.”
1. _______ 2. _______ 3. _______ 4. _______ 5. _______
6. _______ 7. _______ 8. _______ 9. _______ 10. _______
答案：1. different 2. easily 3. about 4. number 5. worried/worrying
6. playing 7. but 8. enjoyed 9. interested 10. really

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