条件状语从句.doc

条件状语从句初中英语条件状语从句一if 引导的条件状语从句引导条件状语从句最常用的连词是if,常见的if条件状语从句表示在某条件下，某事很可能发生，条件是可能存在的,主句中某种情况发生的概率也是很高的。如： If you ask him，he will help you如果你请他帮忙,他会帮你的。 If you fail in the exam，you will let him down如果你考试不及格,你会让他失望的。 If you have finished the homework，you can go home如果你作业做完了就可以回家了。 另外，if从句还表示不可实现的条件或根本不可能存在的条件，也就是一种虚拟的条件或假设。从句多用一般过去时或过去完成时，表示对现在或过去的一种假设。如： If I were you，I would invite him to the party如果我是你，我会邀请他参加聚会。 I would have arrived much earlier if I had not been caught in the traffic要不是交通堵塞，我本会来得早一些。另外你还要注意if 条件句的时态搭配1if从句用一般现在时，主句用一般将来时 If he runs, hell get there in time。 如果他用跑的，他就会及时赶到那儿。The cat will scratch you if you pull her tail。 如果你拉猫的尾巴，它就会抓你。2if从句用一般现在时，主句用may/might/canIf the fog gets thicker， the plane may/might be diverted. 如果雾在大一些，飞机可能就会改在别的机场降落。If it stops snowing， we can go out。 如果雪停了，我们就可以出去。3if从句用一般现在时，主句用must/shouldIf you want to lose weight, you must/should eat less bread. 如果你想减肥，你必须少吃面包.4if从句用一般现在时，主句用一般现在时If you heat ice， it turns to water。 （也可用will turn）如果把冰加热,它就会化成水.5if从句用现在进行时,主句用一般将来时If you are looking for Peter， youll find him upstairs。 如果你是在找彼得，上楼就会找到他。6if从句用现在完成时，主句用一般将来时If you have finished dinner， Ill ask the waiter for the bill。 如果你吃完了，我就叫服务生来算账注意 ：学习 if ” 引导的条件状语从句的用法，现在总结一下: if 条件句不一般，几个要点记心间； 条件句，放在前，逗号要放句中间。 条件句表可能，主句多用将来时; 条件句表事实，主句常用现在时。在 if 引导的条件状语从句中,如果从句谈论的是一个有可能发生的事实及其产生的相关的结果，主句用一般将来时态,从句用一般现在时态。如： We can walk there if we cant find a bus. If it rains tomorrow， we will not go to the zoo。 What will you do if you find a panda in danger?如果 if 条件句谈论的是重复发生和预示要发生的情景和事件，则主从句大多用一般现在时态.如： If bears are in danger， they attack people.在 if 引导的条件状语从句中，if 和条件句位置灵活，可直接放在主句后面，若 if 条件句放句首， 从句后面要加逗号，和主句隔开。还要注意前后时态一致原则补充： “祈使句 + and （or）+ 陈述句”在意思上相当于一个带有条件状语从句的复合句。Hurry up, or youll be late。If you dont hurry up, youll be late.Study hard and you will pass the exam。If you study hard， you will pass the exam。二。 unless引导的条件状语从句unless的意思是如果不，除非.可与if.。.not互换.You will fail in English unless you work hard。你英语考试会不及格的，除非你更加努力。同义句转换：_ _， or you will fail in English.You will fail in English _ _ _ work hard。 三。as /so long as引导的条件状语从句 as /so long as意思是“只要”So long as youre happy， I will be happy。只要你高兴，我就高兴。四。once引导的条件状语从句once引导的条件状语从句，意为“一旦.。，就”，从句可置于主句前或后Once you begin， never stop.一旦开始，就绝不要停止Maths is easy to learn once you understand the rules.一旦你理解了规则，数学就不难学了.提示：在条件状语从句中，用一般现在时代替一般将来时，用一般过去时代替过去将来时.If the weather is bad next week, well put off the climbing.如果下周天气不好，我们将推迟爬山。Father told me if I worked hard he would buy me a gift.爸爸告诉我，如果我努力学习，他会给我买一份礼物。五、if 条件状语从句的时态练习 I. 用所给词的适当形式填空1。If you _(feel) tired， you _ （have） to have a rest.2。 Where _ he _(see) the film if he _（have） time?3. If there _（be） fewer trees， there _( be) more pollution.4. He _(dress) more casually if he _( not work） on weekends.5. If Marcia _（live） alone， she _( keep） a pet parrot.6. Lana _（ buy） a new dress if the old one _(be） out of style。7。The twins _（fight) if they_(argue).8。 I _（have) a bake sale if I _（need） money for education.9。 Peter _( send） me a beautiful souvenir if he _（tour) Spain.10。 If Mr Green _(say) I am hard working， my parents _（ feel） glad.11.I _（go) to the beach if it_ （ not rain) this week.12. _they _( have） a match if the P.E。 teacher _(be） busy？13。He _（write) a letter to his grandparents if he _(get） his report card this week。14。 If she _(get） up late， she _ （ not catch) the early bus。15. Peter _(major) in English if he _（pass） the exams in Peking University.II.单项选择1。If you _ to the party, youll have a great time。 A。 will go B。 went C. go D。 going2. It will be a long time _ Peter _ his work。 A. since, has finished B. after, finishes C。 when, will finish D。 before， finishes。3. What will father _ us from Japan? A。 take B。 bring C。 carry D。 make 4。 Weifang is famous _ kites. A。 for B。 to C. on D。 with5I _ her the answer if she _me. A. can tell， will ask B。 will tell, will ask C. would tell, ask D. will tell, asks6. 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 rain7.Do you know when he will come back tomorrow?-Sorry, I dont know。 When he _ back, Ill tell you。 A. comes B. will come C。 come D. may come 8。 What will you do if you _ to the old folks home visit？A. go B。 went C。 going D。 will go9。 If I eat _ food, Ill be very fat.A。 too many B。 many too C. too much D. much too10。 Ill give the book to him if he _ here next Sunday.A。 will come B。 comes C。 is coming D。 came11。 There _an English film in our school tomorrow。A. is going to have B. will have C。 is going to be D. has12。 Could you tell us where _？A. will the next Olympic Games held B. the next Olympic Games will be heldC. would the next Olympic Games be held D. the next Olympic Games would be held13. When my mother returned last night， I _ a book. A。 read B。 am reading C。 was reading D。 am going to read14。What _ you _ when it began to rain？A. do， do B. were, doing C. are， doing D。 did， do15. Ill wake you up when he _back.A. will B. is going to come C。 comes D. come