if条件状语从句-课件.ppt

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1、If you cool water, it turns into ice. if clause从句从句main clause主句主句 1. If you heat metal, it melts. 如果把金属加热，它就会融化如果把金属加热，它就会融化。 2.Water turns into ice if you cool it. 如果你冷却水，它就会变成冰如果你冷却水，它就会变成冰。if clause从句从句main clause主句主句从句从句主句主句从句从句主句主句从句在主句前时，从句在主句前时，_ （用（用/不用）逗号隔开不用）逗号隔开当主句在前时，则当主句在前时，则_ （用（用/不用）

2、逗号不用）逗号不用用If you drop a glass, it breaks.If you heat ice, it melts.If you stand in the rain, you get wet.主句和从句都用主句和从句都用_(时态时态)因为因为if引导的条件句说的是引导的条件句说的是_一般现在时一般现在时客观事实客观事实/普遍现象普遍现象Actions with definite results 读下列例句，试着自己总结读下列例句，试着自己总结if if 的用法：的用法： 1. If you heat metal, it melts. 如果把如果把金属加热金属加热，它就会融化，

3、它就会融化。 2.Water turns into ice if you cool it. 如果你冷却水，它就会变成冰如果你冷却水，它就会变成冰。 3.If you stand in the rain, you get wet. 如果你站在雨里，就会淋湿。如果你站在雨里，就会淋湿。 4.If you drop a glass, it breaks. 如果你把玻璃杯掉在地上，它就会碎。如果你把玻璃杯掉在地上，它就会碎。 由例句我们可以知道： 如果if引导的条件句谈论的是一种_ 时，主句谓语动词便不用shall/will+动词原形，而直接用_时的动词形式。真理真理/ 客观事实客观事实一般现在一般现

4、在 Water _ (turn) into ice if you _ (cool) it. If you _ (stand) in the rain, you _ (get) wet.turnscoolstandget - b - d - g - a - h - c - f - e1. If you _water.2. A balloon _ it.3. If you _water.4. Metal _it.5. Wood _water.6. A glass_ it.heat ice, it turns intobursts if you stick a pin into cool steam

5、, it turns intomelts if you heatfloats if you put it intobreaks if you dropActions with possible results 读下列例句，总结读下列例句，总结if if 的用法：的用法： 1.If he runs, hell get there in time. 如果他跑步去，就会及时赶到那。如果他跑步去，就会及时赶到那。 2.He will help you if you ask him. 如果你请他帮忙，他会帮你的。如果你请他帮忙，他会帮你的。 3.If you fail in the exam, you

6、will let him down. 如果你考试失败了，你会让他失望的如果你考试失败了，你会让他失望的 4.If you get up late, you will be late for school. 如果你起床晚了，上课就会迟到。如果你起床晚了，上课就会迟到。 由例句我们可以知道： 在if 引导的条件状语从句中，如果从句谈论的是一个有可能发生的事实有可能发生的事实以其产生的相关结果，从句用_, 主句用_.一般现在时态一般现在时态一般将来时态一般将来时态(主将从现主将从现) I _(stay) at home if it _ (rain) tomorrow. If he _ (not co

7、me), I _(go) swimming alone. will stayrainsdoesnt comewill goIf you get up late, you will be late for school.get up latelate for schoolIf the telephone rings, I will answer it. ringanswerIf I have a lot of money, I will buy a big house.a lot of moneya big househard-workingIf sheIf she isis hard-work

8、ing, hard-working, sheshe willwill get good grades.get good grades.get good gradesget good gradesgo fishing .If it is sunny this Sunday, Ill go fishing .sunny this SundayP105 B William has five problems Give him some advice from column A and B 1 I sometimes forget to take the right book to school. I

9、f you check your timetable every night , youll know which books to take. 一、判断正误，如果有误，请更正一、判断正误，如果有误，请更正1. If you will do more exercise this summer, you will be very fit. 2. The candle burns , if you light it.will do do把逗号去掉把逗号去掉3. I will build many schools for the poor children if I win a billion do

10、llars. 4. If you freeze water, it will turn into ice. 5. My uncle visits the museum if he will have time.正确正确will turn turnsvisits will visit, will have hasIf 的两个意思:If: “如果如果”“是否是否”引导条件状语从句引导条件状语从句引导宾语从句引导宾语从句I dont know if he will come tomorrow.I will go to the cinema if it doesnt rain.主现从现主现从现/主将从

11、现主将从现if可用将来时可用将来时 Betty will visit the History Museum if it _ (rain) tomorrow. Ben wants to know if it_ (be) fine tomorrow.If 引导的条件状语从句不用将来时，意思为“如果”。If 引导的宾语从句可以用将来时，意思为“是否”。doesnt rainwill beExercises : He will help me with my maths if he _ free. A was B will be C would be D isI dont know_ he will

12、come tomorrow._ he comes, Ill tell you. A if; Whether B whether; Whether C if; That D if ; If3. Please tell her my telephone number if she _ (want) to know.wantsDD4. Will you come and stay with us for a while if you _ (finish) doing your homework?Wang doesnt know if there _ (be) an English evening n

13、ext week.Mike asked me if we _ (ask) any questions the next class.We are going for picnic tomorrow. Ill call Wendy to make sure_. A why to start B when to start C what to start D which to startwould askfinishwill beB8. - Would you please tell me_ next? - Think it over. Youll find a good way. A when

14、to do B how to do C what to do D where to do9. I dont know if my uncle _. If he _, I will be very happy. A comes; will come B will come; will come C comes; comes D will come; comes10. Either you or I _ going to Shanghai. Only one person may go there. A are B were C am D was CDC( ) 11. If it _ sunny

15、tomorrow, I _ boating. A. is go B. will be, go C. is, will go D. will be, will go ( ) 12. - what will you do if it _ tomorrow, -Ill stay at home and watch TV. A. rain B. rains C. will rain D. is raining CB ( ) 13. If he _, I _ him the time.A. comes, tell B. will come, will tellC. comes, will tell D.

16、 will come, tell( ) 14. If it _, it _cold.A. snows, will be B. snows, isC. will snow, will be D. will snow, is( )1 5. If you _a stone into water, it _.A. put, sinks B. put, will sinkC. will put, sinks D. will put, will sinkCB A 11. He_ (help) me with my maths if he _ (be) free.12. I dont know if Jim

17、 _ tomorrow. If he _, I will be very glad. (come)13. _ (tell) her my telephone number if she _(want) to know.14. If it _ (be) sunny tomorrow, I _ (go) boating. 15. If you _ (boil) water, it _ (turn) into steam.16. You can _ (travel) around the world if you _ (have) money.will helpiswill comecomesTel

18、lwantsiswill goboilturnstravelhaveTranslate the following sentences:1. 如果你请他帮忙,他会帮你的。 If you ask him, he will help you.2. 如果你考试不及格,你会让他失望的。 If you fail in the exam, you will let him down.3. 如果你作业做完了就可以回家了。 If you have finished the homework，you can go home4. 如果熊陷入危险，它们就攻击人。 If bears are in danger, th

19、ey attack people. 5. 如果我早早地到那里，我就可以快点看病。 If I get there early，I can see the doctor quickly. 翻译下面句子。1.如果明天不下雨的话，我就和同学们去动物园。2. 如果周六你去购物的话，我就去。If it doesnt rain tomorrow, I will go to the zoo with my classmates. I will go shopping on Saturday if you go. 3.如果可能的话，我就去火车站接你。4.如果你想减肥，就锻炼身体吧。 If possible, Ill meet you at the railway station.Take some exercise if you want to be thinner/ lose weight. 结束结束