if條件狀語從句和賓語從句

1、Adverbial Clause of Conditionif 引導(dǎo)的條件狀語從句引導(dǎo)的條件狀語從句& &賓語從句賓語從句-復(fù)習(xí)課復(fù)習(xí)課She is doing her homework.If you are hard-working, you will get good grades.She gets good grades.If you play computer games on weekdays ,youll be very tired in classyour parents will be sad.you wont get good grades.your eyes will be

2、 poor1) 條件狀語從句通常由if或或unless(=if not)引導(dǎo)，從句中常用一般時(shí)代替將來時(shí)一般時(shí)代替將來時(shí)，即if或unless后的句子謂語用一般現(xiàn)在時(shí)。但是，主句則通常用將來時(shí)，情態(tài)動詞或祈使句。 時(shí)態(tài)主將從現(xiàn)時(shí)態(tài)主將從現(xiàn)主句一般將來時(shí)，主句一般將來時(shí)，從句一般現(xiàn)在時(shí)從句一般現(xiàn)在時(shí)1. 如果主句是一般將來時(shí)，從句則用一般現(xiàn)在時(shí)。如果主句是一般將來時(shí)，從句則用一般現(xiàn)在時(shí)。 If it rains（從句），（從句）， I will stay at home. Ill go with you if you dont want to go alone（從句）（從句）. 2.如果主句含有

3、如果主句含有must, may, can 等情態(tài)動詞，從句也要用等情態(tài)動詞，從句也要用一般現(xiàn)在時(shí)。一般現(xiàn)在時(shí)。 If you drive too fast, you may have an accident. You must stop if the traffic light is red.3. 如果主句是祈使句，從句同樣要用一般現(xiàn)在時(shí)。如果主句是祈使句，從句同樣要用一般現(xiàn)在時(shí)。 Dont go and play football if you dont finish your homework. Please call me if he comes next Sunday. if條件狀語從

4、句結(jié)構(gòu)及時(shí)態(tài)條件狀語從句結(jié)構(gòu)及時(shí)態(tài)Revision If 引導(dǎo)條狀語從句時(shí)，從句中用一般現(xiàn)在時(shí)代替一般將來時(shí)。1. If he _(go) to the movies,he wont finish his work.goes 2. If I _(become) a doctor,I can help others. become3. If we _(have )time, we will go to the park tomorrow.have4.如果你去，如果你去， 我也去。我也去。If you go,I will go.5.如果明天下雨，請帶雨衣如果明天下雨，請帶雨衣。 raincoatP

5、lease take a raincoat if it rains.If you are free this weekend,what will you do ?If I am free ,sleepwatch TVplay computer gamespracticeIf you want to get good marks,do what? Dont do what? If you want to get good marks, _. If you want to get good marks, dont _. study hard listen to teachers carefully

6、. do homework by yourself. copy your homework. talk in the class cheat in the examsIf 條件句的替代形式：條件句的替代形式：（1）祈使句祈使句 + and/or + 陳述句陳述句（謂語動詞通常用將來時(shí)態(tài)（謂語動詞通常用將來時(shí)態(tài)）。其中，）。其中，and表示句意順承；表示句意順承；or表示轉(zhuǎn)折，意為表示轉(zhuǎn)折，意為“否則否則”。e.g. If you work hard, youll pass the exam easily. = Work hard, and youll pass the exam easily.

7、If you dont work hard, youll fall behind others. = Work hard, or youll fall behind others.（2）用介詞）用介詞with, without的替代形式：的替代形式： e.g. If there is no water, the fish may die. = Fish may die without water. If you help me, Ill finish my task on time. =With your help, Ill finish my task on time.If 在賓語從句中翻譯

8、為在賓語從句中翻譯為“是否是否”If 在條件狀語從句中翻譯為在條件狀語從句中翻譯為“如果如果”Ill go to see you if I am free next week. I want to know if he is a teacher.whether1. if 在句中的含義不同在句中的含義不同2. if 在從句中的位置不同在從句中的位置不同If 引導(dǎo)的賓語從句放在主句之后；而引導(dǎo)的賓語從句放在主句之后；而if引引導(dǎo)的狀語從句可放在主句之前也可放在主導(dǎo)的狀語從句可放在主句之前也可放在主句之后句之后= If it doesnt rain, I will go out tomorrow.I

9、 will go out tomorrow if it doesnt rain.I dont know if the train has arrived. If 引導(dǎo)的條件狀語從句放于句首時(shí)多用逗號隔開；引導(dǎo)的條件狀語從句放于句首時(shí)多用逗號隔開；而而if引導(dǎo)的賓語從句則不能。引導(dǎo)的賓語從句則不能。3. 時(shí)態(tài)要求上有區(qū)別時(shí)態(tài)要求上有區(qū)別If 引導(dǎo)條件狀語從句的時(shí)態(tài)為一般現(xiàn)在時(shí)引導(dǎo)條件狀語從句的時(shí)態(tài)為一般現(xiàn)在時(shí) 記住記住“主將從現(xiàn)主將從現(xiàn)” 1.I want to know if there a sports meeting next month.doesnt rainwill be2.If it

10、 doesnt rain ,well go outIf 引導(dǎo)的賓語從句的時(shí)態(tài)由主句及本身時(shí)引導(dǎo)的賓語從句的時(shí)態(tài)由主句及本身時(shí)態(tài)決定；態(tài)決定；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 each other , we will get good results .1 If I _(not understand）, I will ask my

11、 teacher for help .2 If I _(copy ) your homework , I will cheat myself .3 I dont know if it _ (rain) tomorrow.4 My teacher asked me if I _ (finish) my homework already. dont understand copy will rain had finishedif的用法的用法2.引導(dǎo)條件狀語從句：引導(dǎo)條件狀語從句：譯為譯為“如果，假如如果，假如”(1) if從句從句+祈使句祈使句(2) if從句從句+主句（一般將來時(shí)）主句（一般將來時(shí)）(3) if從句從句+主句（含有情態(tài)動詞）主句（含有情態(tài)動詞） 1.引導(dǎo)賓語從句引導(dǎo)賓語從句