if条件状语从句和宾语从句-PPT.ppt

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1、Adverbial Clause of Conditionif 引导的条件状语从句引导的条件状语从句&宾语从句宾语从句-复习课复习课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 poo

2、r1)条件状语从句通常由if或或unless(=if not)引导，从句中常用一般时代替将来时一般时代替将来时，即if或unless后的句子谓语用一般现在时。但是，主句则通常用将来时，情态动词或祈使句。时态主将从现时态主将从现主句一般将来时，主句一般将来时，从句一般现在时从句一般现在时1.如果主句是一般将来时，从句则用一般现在时。如果主句是一般将来时，从句则用一般现在时。If it rains（从句），（从句），I will stay at home.Ill go with you if you dont want to go alone（从句）（从句）.2.如果主句含有如果主句含有must,

3、may,can 等情态动词，从句也要用等情态动词，从句也要用一般现在时。一般现在时。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，从句同样要用一般现在时。如果主句是祈使句，从句同样要用一般现在时。Dont go and play football if you dont finish your homework.Please call me if he comes next Sunday.if条件状语从句结构及时态条件状语从句结构及时态Rev

4、ision If 引导条状语从句时，从句中用一般现在时代替一般将来时。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，请带雨衣如果明天下雨，请带雨衣。raincoatPlease take a raincoat if it ra

5、ins.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.do homework by yourself.copy your hom

6、ework.talk in the class cheat in the examsIf 条件句的替代形式：条件句的替代形式：（1）祈使句）祈使句+and/or+陈述句（谓语动词通常用将来时态）陈述句（谓语动词通常用将来时态）。其中，。其中，and表示句意顺承；表示句意顺承；or表示转折，意为表示转折，意为“否则否则”。e.g.If you work hard,youll pass the exam easily.=Work hard,and youll pass the exam easily.If you dont work hard,youll fall behind others.=W

7、ork hard,or youll fall behind others.（2）用介词）用介词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 引导的条件状语从句和引导的条件状语从句和if 引导的宾语从引导的宾语从句的区分句的区分:If 在宾语从句中翻译为在宾语从句中翻译为“是否是否”

8、If 在条件状语从句中翻译为在条件状语从句中翻译为“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 在句中的含义不同在句中的含义不同2.if 在从句中的位置不同在从句中的位置不同If 引导的宾语从句放在主句之后；而引导的宾语从句放在主句之后；而if引引导的状语从句可放在主句之前也可放在主导的状语从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 will go out tomorrow

9、 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；引导的条件状语从句放于句首时多用逗号隔开；而而if引导的宾语从句则不能。引导的宾语从句则不能。3.时态要求上有区别时态要求上有区别If 引导条件状语从句的时态为一般现在时引导条件状语从句的时态为一般现在时 记住记住“主将从现主将从现”1.I want to know if there a sports meeting next month.doesnt rainwill be2.If it doesnt rain,well go out

10、If 引导的宾语从句的时态由主句及本身时引导的宾语从句的时态由主句及本身时态决定；态决定；找出下列句子中哪些是找出下列句子中哪些是if条件状语从句，哪些是条件状语从句，哪些是if宾语从句宾语从句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 each other,we will get good results.If 引导的条件状语引导的条件状语从句或宾

11、语从句的从句或宾语从句的练习练习1 If I _(not understand）,I will ask my teacher for help.2If I _(copy)your homework,I will cheat myself.3I dont know if it _ (rain)tomorrow.4My teacher asked me if I _ (finish)my homework already.dont understand copy will rain had finishedif的用法的用法2.引导条件状语从句：译为引导条件状语从句：译为“如果，假如如果，假如”(1)if从句从句+祈使句祈使句(2)if从句从句+主句（一般将来时）主句（一般将来时）(3)if从句从句+主句（含有情态动词）主句（含有情态动词）1.引导宾语从句：译为引导宾语从句：译为“是否是否”，表示不确定的概念。时态特征为：宾，表示不确定的概念。时态特征为：宾语从句的时态一致性（主过从过，主现从自由）语从句的时态一致性（主过从过，主现从自由）I didnt know if your father could come together.Can you tell me if miss your parents?