第35课时
第33课时
由引导词if引导的状语从句叫做条件状语从句。在英文中，条件是指某一件事情实现之后（状语从句中的动作），其它事情（主句中的动作）才能发生，通常译作“假如”、“如果”。一.if的位置：if“如果”，当引导条件状语从句时，既可以放在主句前面，也可以放在主句后面。若if引导的条件句放在句首，从句后面要加逗号与主句隔开。例如：My mother will take me to the park if she is free.如果我妈妈有空，她就会带我去公园。
（此句中“My mother will take me to the park”为主句“if she is free”为if引导的条件状语从句。if引导的条件状语从句位于主句之后，所以不需要逗号隔开）
If my mother is free, she will take me to the park.如果我妈妈有空，她将会带我去公园。
（此句if引导的条件状语从句位于句首，主句位于其后，所以要用逗号隔开）
二.时态的运用
注意：在if的条件状语从句中，主句为下列情形之一时，if条件状语要用一般现在时。
1.主句是一般将来时（主将从现）
例如：If he comes, he will tell me all.如果他来了，他会告诉我所有（的事情）。
（这个知识点在初中阶段是常考题，简称“主将从现”——主句是一般将来时态，从句是一般现在时态。本句中主句是由will引导的一般将来时态的句子，从句是由if引导的一般现在时态的句子，符合主将从现的法则。）
2.主句是含有情态动词may/might/can/must/should等句子。
例如：If you want to lose weight, you must eat less bread.如果你想减肥，你必须少吃面包。
（主句中含有情态动词must，所以if引导的条件状语从句要用一般现在时态。）
3.主句是祈使句
例如：If you are not strong enough, please don't take part in such an activity.如果你不够强壮，请不要参加这种活动。
（：主句是一个Do型的祈使句，所以根据原则，if从句要用一般现在时态。——不清楚Do型祈使句的小伙伴可以查看冉老师历史发文记录）
三.句型的相互转换
借助“祈使句+and/or+句子（一般将来时结构）”这一句型来转换，在句子中，and表示顺承，or表示“否则”。
例如：If you work hard, you'll success.如果你努力学习，你将会成功。=work hard，and you'll success.努力学习，那么你将会成功。=Work hard or you won't success.努力学习，否则你不会成功。
（同学们注意and和or的翻译，在日常写作中也可以和if引导的条件状语从句相互转换，增加自己文章的看点。）2.借助without/with来转换条件状语从句。
例如：If there is no water, fish will die.如果没有水，那么鱼就会死。=Fish will die without water.没有水，鱼将会死。
（补充——without是介词，所以在学习中同学们注意介词后面要加ing）If you help me ， I'll finish the work.如果你帮助我，我将会完成这项任务（主将从现）=with your help, I'll finish the work soon.找你的帮助下，我将会完成这项任务.
（第一个句子采用的是if引导的条件状语从句，且遵循“主将从现”的原则。第二个借助的是介词with，两句都含有对将来事情推测的含义。）
（ ）1.We'd better hurry ______ it is getting dark.A.and B. but C. as D. unless（ ）2. I didn' t manage to do it _____ you had explained how.A. until B. unless C. when D. before（ ）3._____ he comes, we won't be able to go.A. Without B. Unless C. Except D. Even（ ）4. I hurried _____ I wouldn't be late for class.A. since B. so that C. as if D. unless（ ）5. _____ I catch a cold, I have pain in my back.A. Every time B. Though C. Even D. Where（ ）6. What's the matter _____ they still haven't answered the telegram?A. when B. that C. though D. however（ ）7. Bring it nearer _____ I may see it better.A. although B. even though C. so that D. since（ ）8. You may arrive in Beijing early _____ you mind taking the night train.A. that B. though C. unless D. if（ ）9. Helen listened carefully _____ she might discover exactly what she needed.A. in that B. in order that C. in case D. even though（ ）10. More people will eat out in restaurants _____ they do today.A. than B. when C. while D. as（ ）11._____ hard she tries, she can hardly avoid making mistakes in her homework.A. Much B. However C. As D. Although（ ）12. Poor _____ it may be, there is no place like home, _____ you may go.A. as; wherever B. though; whenever C. in spite of; when D. that; wherever（ ）13. The child was __ immediately after supper.A. enough tired to go to bed B. too tired to go to bedC. so tired that he went to bed D. very tired, he went to bed（ ）14. The history of nursing __ the history of man.A. as old as B. is old than C. that is as old as D. is as old as（ ）15. _____ born in Chicago, the author was famous for his stories about New York.A. Since B. Once C. When D. Although（ ）16._____ we stood at the top of the building, the people below were hardly visible.A. As B. Although C. Unless D. In spite of（ ）17. Scarcely was George Washington in his teens _____ his father died.A. than B. as C. while D. when（ ）18. _____ David goes, he is welcome.A. Whichever B. However C. Wherever D. Whatever（ ）19. The house stood _____ there had been a rock. A. which B. at which C. when D. where（ ）20. Small _____ it is, the pen is a most useful tool.A. because B. so C. if D. as（ ）21. After the new technique was introduced, the factory produced cars in 1988 as the year before.A. as twice many B. as many twice C. twice as many D. twice many as（ ）22. The piano in the other shop will be _____, but _____.A. cheaper; not as better B. more cheap; not as betterC. cheaper; not as good D. more cheap; not as good（ ）23. John plays football _____, if not better than, David.A. as well B. as well as C. so well D. so well as（ ）24. Although he is considered a great writer,A. his works are not widely read B. but his works are not widely readC. however his works are not widely read D. still his works are not widely read（ ）25. ___ the day went on, the weather got worse.A. With B. Since C. While D. As（ ）26.—What was the party like? —Wonderful. It' s years _____ I enjoyed myself so much.A. after B. when C. before D. since（ ）27. It was not _____ she took off her dark glasses _____ I realized she was a famous film star.A. when; that B. until; that C. until; when D. when; then （ ）28. If we work with a strong will, we can overcome any difficulty, _____ great it is.A. what B. how C. however D. whatever（ ）29. After the war, a new school building was put up _____ there had once been a theatre.A. that B. where C. which D. when（ ）30._____, Mother will wait for him to have dinner together.A. However late is he B. However he is lateC. However is he late D. However late he is 推荐阅读
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