If引导的条件状语从句.ppt

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1、If引导的条件状语从句,潘店镇中学,语法：,例句：If people obey the traffic rules, there will be fewer accidents.,if引导的条件状语从句,if:从属连词，意思是：“如果，假如，倘若”,从句,主句,There will be fewer accidents if people obey the traffic rules.,原句可改为：,if引导的条件状语从句既可以放在句子前， 也可以放在句子后。 从句位于主句之前时，常用逗号将其与主句隔开。,结构：,主句谓语中也可以含有情态动词，如：must,can,could,should等,

2、时态：,if引导的条件状语从句， 主句用一般将来时（will）,从句用一般现在时。,例句：If people obey the traffic rules, there will be fewer accidents.,主句谓语中也可以用had better(not)do,提建议,例句：如果交通指示灯是红的，你必须停下来等一等。,eg:If the traffic lights are red,you must stop and wait.,例句：如果你想减肥，你最好锻炼。,eg:If you want to lose weight,you had better take some exerc

3、ise.,“主将从现”,if的反义词：if.not.=unless,意思是：“如果不，除非”,I wont go there unless I hear from you.(同义句) I wont go there _ I _hear from you.,if dont,I wont go to the party if I am not invited. (同义句) I wont go to the party_ I am invited.,unless,变换：,1.有if引导的条件状语从句的复合句中，当主句和从句的 主语均为you时，可转换为“祈使句，and+简单句”或 “祈使句，or+简

4、单句”,You can pass the exam if you work hard. -，and you will pass the exam.,If you dont hurry up,you will be late again. Hurry up,- you will be late again.,Work hard,or,2. 借助介词with 或without来转换。 例如: If you help me, Ill finish my job soon. -, Ill finish my job soon. 如果你帮我，我将很快完成我的工作。 If there is no wate

5、r, fish may die. Fish may die -. 如果没有水，鱼可能会死。,With your help,without water,注意事项 1. 在if引导的条件状语从句中，当主句是一般将来时时，不能够使用be going to结构，而要用will。 例如： Ill help you with your English if I am free tomorrow. 如果明天我有空，我会帮你学英语。 2. 在if引导的条件状语从句中不能够使用some，而要用any。 例如： If you have any questions to ask, please come to my

6、 office. 如果你有问题要问的话，请到我办公室来。,if 引导的条件状语从句和if 引导的宾语从句的区分:,If 在宾语从句中翻译为“是否” If 在条件状语从句中翻译为“如果”,Ill go to see you if I am free next week.,I want to know if he is a teacher.,whether,1. if 在句中的含义不同,2. if 在从句中的位置不同,If 引导的宾语从句放在主句之后；而if引导的状语从句可放在主句之前也可放在主句之后,= If it doesnt rain, I will go out tomorrow.,I w

7、ill go out tomorrow if it doesnt rain.,I dont know if the train has arrived.,If 引导的条件状语从句放于句首时多用逗号隔开； 而if引导的宾语从句则不能。,找出下列句子中哪些是if条件状语从句，哪些是if宾语从句,1. Can you tell me if she can come to the meeting ? 2. She will not go there if it is rainy tomorrow. 3. I cant guess if she will be angry . 4. If we help

8、 each other , we both will get good results .,3. 时态要求上有区别,If 引导条件状语从句的时态为一般现在时 记住“主将从现”,1.I want to know if there a sports meeting next month.,doesnt rain,will be,2.If it , well hold it.,If 引导的宾语从句的时态由主句及本身时态决定；,If 引导的条件状语从句的练习,1 If I _(not understand）, I will ask my teacher for help . If I _(copy )

9、 your homework , I will cheat myself . 3 If she _(not get ) up early , shell miss the early bus . 4 If your mother_ (buy) the book for you , it will be good for your study.,dont understand,copy,doesnt get,buys,5. If you _(not work ) hard , you _(not pass) the exam. 6. If she _(mend) the computer , h

10、er father _(not blame ). 7. If your brother _(break) the window , he will feel very sorry for that . 8. If the computer (not work), mend it please .,dont work,wont pass,mends,wont blame,breaks,doesnt work,9. If she _(not be) interested in math, she will find it very boring . 10. If you _(get ) high

11、scores, your parents will be proud of you . 11. If you _(be) happy , we will be happy . 12. If she (translate ) the sentence word by word , she _(get ) its true meaning .,isnt,get,are,translates,will get,1.If you _ to the party, youll have a great time. A. will go B. went C. go D. going 2 I _ her th

12、e answer if she _me. A.can tell, will ask B. will tell, will ask C. would tell, ask D. will tell, asks,C,D,3. What are you going to do tomorrow? -Well go to the library tomorrow if it _. A. isnt rain B. rain C. wont rain D. doesnt rain 4. What will you do if you _ to the old folks home visit? A. go B. went C.going D. will go,A,D,See you !,