Unit 7 条件句.doc

八上Unit 7 Memory-GrammarConditional sentences 条件句 If引导条件状语从句（1）If 条件句：表示客观真理或客观事实，两个动词时态一致-一般现在时If you take a fish out of water（从句）, it dies（主句). If you cool steam, it turns into water. If 条件从句可以放在前面，也可以放在后面，放前面时，后面常用逗号隔开If you cool water ,it turns into ice .It turns into ice if you cool water .（2）if条件句：有可能性结果发生的行动，在这些句子中，动词的时态是不同的，if 引导的条件状语从句中，主句用一般将来时态，从句用一般现在时态（主将从现） If it doesnt rain, well have a picnic tomorrow.If we go by bus，it will be cheaper. If you dont hurry, youll miss the trainIf the picture is silly ,strange and colourful ,you will remember it better .If I have time, I am going to visit you .I will go to the park if it doesnt rain tomorrow(3) 主祈从现（祈使句+if+一般现在时态） Put up your hands if you have any questions to ask. If its cold later tonight，take your coat with you. Dont wait for me if Im late. (4)主情从现（情态动词+if +一般现在时态） If I get there early, I can see the doctor quickly.I may buy a car if I pass my driving test. If you go to another country，you must obey the local laws. 注意： 当主语是you时， if 引导的条件状语从句=“祈使句+and/ or +简单句”。 and 表示顺承，or 表示转折， 意为“否则”。Work hard, and you will make great progress.=If you work hard, you will make great progress.Take care , or you will fall off the tree. = If you dont take care, youll fall off the tree. Hurry up, or you will be late. =If you dont hurry up, you will be late.Unless 引导条件状语从句unless :如果不，除非，相当于ifnot (助动词或be动词+not) Unless you listen carefully（从句）, you wont know the answer.（主句） = If you dont listen carefully（从句）, you wont know the answer（主句）.=You should listen carefully, or you wont know the answer.I cant see unless I wear glasses. =I cant see if I dont wear glasses.Unless you can pay your bills, youll have to leave. =If you cant pay your bills, youll have to leave.You will miss the bus unless you hurry up. Youll fail your Chemistry test again unless you work harder.You will never get anywhere unless you set your goal Unless you are friendly to people, you wont get on well with them（与人相处得好）口诀：条件句，放在前，逗号要放句中间，条件句，表可能，主将从现很简单，条件句，表事实，主从现在记心间。拓展延伸：1.If引导宾语从句，意为“是否”（if= whether）,从句用将来时态。 Do you know if he will come here this afternoon?2. when, as soon as, not.until引导的时间状语从句也是用主将从现。典型例题1. I dont know if he _. He will come if it _. Acomes; wont rain Bwill come; doesnt rain Ccomes; doesnt rain Dwill come; wont rain 2. Do you think if_ an English film tomorrow night？ Ais there Bthere is going to have Cthere is going to be Dwill there be 语法针对练习一、 Join the sentences with if.1. The temperature rises t0 100. The room becomes bright.2. You feel cool. It rains.3. You switch on the lights. Water boils,4. The ground gets wet. You turn on the air conditioner.5. You put oil on water. You add 5 and 3,6. You get 8. It floats.1. _2. _3. _ 4. _5. _6. _二、 Put these facts into conditional sentences with if 1. 例题： Doctors treat sick people. If youre a doctor, you treat sick people.2. Vegetarians dont eat meat. If youre a vegetarian, _ .3. People in a hot country dont like cold weather. If you live_.4. Dancers have to be tall and slim. If youre a dancer, _.5. Mechanics understand engines. If youre a_.三、 用括号中所给动词的正确时态完成下列句子.1. If _ (it/rain), _ (we/not/go) out. Well stay at home.2. If _ (the weather/be) nice tomorrow, _ (we/drive) to the coast.3. If _ (she post) the letter now, _ (they/receive) it tomorrow.4. _ (Fiona/be) angry if _ (John/arrive) here late again.5. _ (I/go) to their party if _ (I/have) enough time.6. Unless _ (she/pass) this exam, _ (she/not/get) this job.7. _ (you/learn) a lot if _ (you/take) this course. 8. If _ (I/get) a ticket, _ (I/go) to the concert.9. _ (I/buy) that camera unless _ (it/cost) too much.10. If _ (you/run) very fast, _ (you/catch) the bus.11. _ (I/go) to see the doctor if _ (I/not/feel) better tomorrow.12. If _ (they/win) this game, _ (they/be) the champion.13. If _ (you/get) on the train, just _ (relax) along the way for the whole journey.14. If_ (you/live) in England, _ (not/forget) to drive on the left!四、 选择正确答案。1. -Will you go to Davids wedding party? -I wont go _I am invited. A. because B. and C. but D. unless2. If you_ the water, it _ into gas. A. boil; turns B. boil; will turns C. will boil; turn D. will boil; will turn3. I_ you if I_ free tomorrow. A. visit; will be B. will visit; will be C. will visit, am D. visit, am4. _you have lots of money, you cant buy that house. A. If B. Because C. Unless D. Until5. You will fail the exam _ you dont study hard. A. and B. though C. but D. if6. You wont learn English well _you work hard. A. unless B. when C. if D. because7. _you dont go to bed earlier, you will feel tired tomorrow.A. Unless B. If C. Though D. Until8. I wont come to see you _I am asked to. A. unless B. because C. if D. though9. I wont leave here until he _back. A. come B. comes C. will come D. came10. -Would you like to go shopping with us tomorrow? -Sure, _I am busy. A. since B. unless C. when D. until11. She will come to help us if she _ too busy tomorrow. A. is B. isnt C. will be D. wont be12. -There will be a baseball match this Sunday. Would you like to go with me? -If I have time, I _with you.A. went B. will go C. go D. have watched13. If I find his phone number, I _ you. A. tell B. told C. will tell D. have told14. Youd better look up the new word in a dictionary _ you dont know it. A. if B. that C. though D. whether15. Dont talk loudly at the meeting. If you _, you will have to leave. A. are B. do C. did D. can16. -The art club is for members only. You cant go in_ you are a member. A. unless B. because C. if D. though17. -Why were you late again? -_ I missed the bus. A. Unless B. If C. Because D. When18. Im waiting for my friend. _, Ill go shopping alone.A. If she comes B. If she will come C. If she doesnt come D. If she didnt come19. -Mum, my tooth hurts so much. -If you_ too many sweets, you_ better.A. eat; feel B. stop eating; will feelC. will eat; feel D. dont eat; feel20. -Dad, can I have another cake? -Yes, you can _ you are afraid of_ fat.A. unless; getting B. if; get C. if; getting B. unless; get21. Mike wants to know if_ a picn