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if条件状语从句和宾语从句 PPT_图文

Adverbial Clause of Condition if 引导的条件状语从句&宾语从句 -----------复习课 She is doing her She gets good grades. homework. If you are hard-working, you will get good grades. If you play computer games on weekdays , you’ll be very tired in class your parents will be sad. you won’t get good grades. your eyes will be poor 1) 条件状语从句通常由if或unless(=if not)引导,从句中 常用一般时代替将来时,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 主句一般将来时, 从句一般现在时 Revision if条件状语从句结构及时态 1. 如果主句是一般将来时,从句则用一般现在时。 If it rains(从句), I will stay at home. I’ll go with you if you don’t want to go alone(从句). 2.如果主句含有must, may, can 等情态动词,从句也要用 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。 Don’t go and play football if you don’t finish your homework. Please call me if he comes next Sunday. 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 hego_e_s____(go) to the movies,he won’t finish his work. 2. If I b_e_c_o_m__e__(become) a doctor,I can help others. 3. If we _h_a_v_e___(have )time, we will go to the park tomorrow. 4.如果你去, 我也去。 If you go,I will go. 5.如果明天下雨,请带雨衣。 raincoat Please take a raincoat if it rains. practice If you are free this weekend, what will you do ? sleep If I am free ,… watch TV play computer games If you want to get good marks, do what? Don’t do what? ? If you want to get good marks, _s_tu_d_y_h_a_rd___. listen to teachers carefully. do homework by yourself. ? If you want to get good marks, ? don’t _c_o_p_y_y_o_ur_h_o_m. ework. talk in the class cheat in the exams If 条件句的替代形式: (1)祈使句 + and/or + 陈述句(谓语动词通常用将来时态 )。其中,and表示句意顺承;or表示转折,意为“否则” 。 e.g. If you work hard, you’ll pass the exam easily. = Work hard, and you’ll pass the exam easily. If you don’t work hard, you’ll fall behind others. = Work hard, or you’ll fall behind others. (2)用介词with, without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, I’ll finish my task on time. =With your help, I’ll finish my task on time. 1. if 在句中的含义不同 I want to know if he is a teacher. whether If 在宾语从句中翻译为“是否” I’ll go to see you if I am free next week. If 在条件状语从句中翻译为“如果” 2. if 在从句中的位置不同 I don’t know if the train has arrived. I will go out tomorrow if it doesn’t rain. = If it doesn’t rain, I will go out tomorrow. 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 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。 3. 时态要求上有区别 1.I want to know if there will be meeting next month. a sports If 引导的宾语从句的时态由主句及本身时 态决定; 2.If it doedso