if引導(dǎo)的條件狀語從句和賓語從句.doc

If的用法if 的條件從句分為真實條件從句和虛擬條件從句。真實條件從句：真實條件從句適用于主將從現(xiàn)，是假設(shè)有可能發(fā)生的。一 位置在if引導(dǎo)的條件狀語從句中，既可以放在主句之前，也可以放在主句之后。若if條件句放句首，從句后面要加逗號，和主句隔開。You will catch the bus if you get up early. = If you get up early, you will catch the bus.二 時態(tài)1.（主祈從現(xiàn)）主句：一般現(xiàn)在時態(tài)（包含祈使句和含有情態(tài)動詞can, may, must等的句子）從句：一般現(xiàn)在時態(tài)2. （主將從現(xiàn)）主句：一般將來時態(tài)從句：一般現(xiàn)在時態(tài)3.從句:現(xiàn)在進行時，主句:一般將來時 IfyouarelookingforPeteryoullfindhimupstairs.如果你是在找彼得，上樓就會找到他。4if從句用現(xiàn)在完成時，主句用一般將來時 IfyouhavefinisheddinnerIllaskthewaiterforthebill.如果你吃完了，我就叫服務(wù)生來算賬5.if條件句談?wù)摰氖侵貜?fù)發(fā)生和預(yù)示要發(fā)生的情景和事件，則主從句大多用一般現(xiàn)在時態(tài)。如：Ifbearsareindanger,theyattackpeople.三 注意事項1. 在if 引導(dǎo)的條件狀語從句中，當(dāng)主句是一般將來時態(tài)時，不能使用be going to 結(jié)構(gòu)，而要用will.2. 在if 引導(dǎo)的條件狀語從句中,不能使用some,而要用any.四 同義句轉(zhuǎn)化1. 借助于祈使句+andor+簡單句轉(zhuǎn)化，and表示順承，or表示轉(zhuǎn)折。例如：(1)If you work hard, youllpass the exam. Work hard, and youll pass the exam. (2)If you dont hurry up, youll be late. Hurry up, or youll be late.2. 借助于介詞with或者without 來轉(zhuǎn)換例如：If you help me, Ill finish my job soon. With your help , Ill finish my job soon.if條件句不一般,幾個要點記心間條件句,放在前,逗號要放句中間。條件句表可能，主句多用將來時；條件句表事實，主句常用現(xiàn)在時。虛擬條件從句:虛擬條件從句是假設(shè)不太可能發(fā)生的。IF的虛擬語氣有三種：內(nèi)容 從句 主句與現(xiàn)在事實相反 動詞過去式（be用were） would/could/should/might+動原與將來事實相反 should/were to+動原 would/could/should/might+動原與過去事實相反 had+過分 would/could/should/might+ have+過分下面三句依次是上面三種情況的例句：If I were you ,I would/could/should/might do that.If I had know that yesterday, I would/could/should/might have told you .If it should rain , the crops would/could/might be saved. If引導(dǎo)的賓語從句 一 if 引導(dǎo)賓語從句時，意思為：是否，從句的時態(tài)通常要和主句保持一致。 【例句】 I want to know if he lives there. 我想知道他是否住在那兒。 He asked me if I could help him. 他問我是否能幫他。【考查點】if、whether引導(dǎo)的賓語從句的區(qū)別 1. if或whether引導(dǎo)賓語從句時，作“是否”講，常放在動詞ask、see、say、know和find out等后面。一般情況下，兩者常可換用，在口語中多用if。 【例句】 Nobody knows whether / if it will rain tomorrow. 沒有人知道明天是否下雨。 Lucy asked whether / if they had a cotton sweater. 露西問他們是否有棉制的毛衣。 二. 注意事項：if或whether引導(dǎo)賓語從句時，要注意三個方面，即連詞、語序和時態(tài)。1. if或whether既不能和that 或其他連詞（副詞）同時使用，也不能省略。 【例句】 我不知道他今天是否會來。 誤 I dont know that if(whether) he will come here today. 正 I dont know if(whether) he will come here today. 他走過來看看貓是否出了毛病。 誤 He came to see what if (whether) there was anything wrong with his cat . 正 He came to see if (whether) there was anything wrong with his cat . 2.if或whether引導(dǎo)賓語從句時，雖具有疑問的意義，但其從句應(yīng)用陳述句的語序。 【例句】Did you know the way to the hospital? The old woman asked me. The old woman asked me if / whether I knew the way to the hospital. 老婦人問我是否知道去醫(yī)院的路。 3. if或whether引導(dǎo)的賓語從句應(yīng)和主句的時態(tài)保持一致。即主句為一般現(xiàn)在時，從句用任一種時態(tài)；主句為一般過去時，從句則用過去時中的任一種時態(tài)。 【例句】 I dont know if (whether) he has come here. 我不知道他是否來過這兒。 Tom asked if (whether) I had read the book. 湯姆問我是否看過這本書。 三If 和whether兩者不能互換的情況1. 只能用whether的情況 在動詞不定式之前只能用whether： 【例句】 I cant decide whether to stay. 我不能決定是否留下。 2. 在whether or not 的固定搭配中： 【例句】 I want to know whether its good news or not. 我想知道它是不是好消息。3. 在介詞后，只能用whether： 【例句】 His father is worried about whether he loses his work. 他的父親擔(dān)心他是否會失去工作。 4.用if會引起歧義時： 【例句】 Could you tell me if you know the answer? 這句話有兩種意思： “你能告訴我你是否知道答案嗎？”或“如果你知道答案，請告訴我，好嗎？”。 如用whether則可避免歧義。 【考題鏈接】 I dont know _ they could pass the exam or not. A. why B. if C. that D. whether 答案：D 解題思路：本題考查if與whether的區(qū)別，在whetheror not的固定搭配中通常只用whether。 練習(xí)題：句型轉(zhuǎn)換 1. Do they want fried chicken? He asked the boys.(改為賓語從句) He asked the boys _they _fried chicken. 2. Was the watch made in Shanghai? I dont know.(改為賓語從句) I dont know _the watch _made in Shanghai. 3. “Do you want to try something new?” Toms mother asked him.(同義句轉(zhuǎn)換) Toms mother asked him _to try something new. 答案：1. if / whether, wanted 2. if / whether, was 3. if / whether he wanted一、用所給詞的適當(dāng)形式填空 1.Ifyou_(feel)tired,you_(have)tohavearest. 3.Ifthere_(be)fewertrees,there_(be)morepollution.5.IfMarcia_(live)alone,she_(keep)apetparrot.6.Lana_(buy)anewdressiftheoldone_(be)outofstyle.9.Peter_(send)meabeautifulsouvenirifhe_(tour)Spain.10.IfMrGreen_(say)Iamhard-working,myparents_(feel)glad.11.I_(go)tothebeachifit_(notrain)thisweek.13.He_(write)alettertohisgrandparentsifhe_(get)hisreportcardthisweek.14.Ifshe_(get)uplate,she_(notcatch)theearlybus.15.Peter_(major)inEnglishifhe_(pass)theexamsinPekingUniversity.16.如果努力學(xué)習(xí)，你就會取得好成績。 Ifyou_,you_good_.17.他如果看電視太久了，他的父母會不高興。 Ifhe_TVtoomuch,hisparents_unhappy.18.如果我們?yōu)樗M織生日聚會，大家都會來的。 Everyone_ifwe_abirthdayparty_him.19.如果明天不下雨，我會和你一起去公園的。 Ifit_tomorrow,I_gotothepark_you.21.如果他有空，他會幫助你的。 Ifhe_,he_you.23.你如果抄同學(xué)的作業(yè)就不能學(xué)好各門功課。 You_goodatallthesubjectsifyou_theotherstudentshomework. 單項選擇（1.Ifyou_totheparty,youllhaveagreattime.A.willgo B.went C.go D.going2.Itwillbealongtime_Peter_hiswork.A.since,hasfinishedB.after,finishesC.when,willfinishD.before,finishes.3.Whatwillfather_usfromJapan?A.takeB.bringC.carryD.make4.Weifangisfamous_kites.A.forB.toC.onD.with5I_hertheanswerifshe_me. A.cantell,willaskB.willtell,willaskC.wouldtell,askD.willtell,asks6.Whatareyougoingtodotomorrow?-Wellgotothelibrarytomorrowifit_. A.isntrain B.rainC.wontrain D.doesntrain7.Doyouknowwhenhewillcomebacktomorrow?-Sorry,Idontknow.Whenhe_back,Illtellyou.A.comesB.willcomeC.comeD.maycome 8.Whatwillyoudoifyou_totheoldfolkshomevisit?A.goB.wentC. goingD.willgo9.IfIeat_food,Illbeveryfat. A.toomany B.manytooC.toomuch D.muchtoo10.Illgivethebooktohimifhe_herenextSunday.A.willcomeB.comesC.iscomingD.came11.There_anEnglishfilminourschooltomorrow. A.isgoingtohaveB.willhaveC.isgoingtobeD.has12.Couldyoutelluswhere_？A.willthenextOlympicGamesheldB.thenextOlympicGameswillbeheldC.wouldthenextOlympicGamesbehel