-24.條件狀語(yǔ)從句

條件狀語(yǔ)從句由引導(dǎo)詞if引導(dǎo)的狀語(yǔ)從句叫做條件狀語(yǔ)從句。在英文中，條件是指某一件事情實(shí)現(xiàn)之后（狀語(yǔ)從句中的動(dòng)作），其它事情（主句中的動(dòng)作）才能發(fā)生，通常譯作“假如”、“如果”。

一.if的位置：if“如果”，當(dāng)引導(dǎo)條件狀語(yǔ)從句時(shí)，既可以放在主句前面，也可以放在主句后面。若if引導(dǎo)的條件句放在句首，從句后面要加逗號(hào)與主句隔開(kāi)。

例如：Mymotherwilltakemetotheparkifsheisfree.如果我媽媽有空，她就會(huì)帶我去公園。（此句中“Mymotherwilltakemetothepark”為主句“ifsheisfree”為if引導(dǎo)的條件狀語(yǔ)從句。if引導(dǎo)的條件狀語(yǔ)從句位于主句之后，所以不需要逗號(hào)隔開(kāi)）

Ifmymotherisfree,shewilltakemetothepark.如果我媽媽有空，她將會(huì)帶我去公園。（此句if引導(dǎo)的條件狀語(yǔ)從句位于句首，主句位于其后，所以要用逗號(hào)隔開(kāi)）二.時(shí)態(tài)的運(yùn)用注意：在if的條件狀語(yǔ)從句中，主句為下列情形之一時(shí)，if條件狀語(yǔ)要用一般現(xiàn)在時(shí)。1.主句是一般將來(lái)時(shí)（主將從現(xiàn)）例如：Ifhecomes,hewilltellmeall.如果他來(lái)了，他會(huì)告訴我所有（的事情）。（這個(gè)知識(shí)點(diǎn)在初中階段是?？碱}，簡(jiǎn)稱“主將從現(xiàn)”——主句是一般將來(lái)時(shí)態(tài)，從句是一般現(xiàn)在時(shí)態(tài)。本句中主句是由will引導(dǎo)的一般將來(lái)時(shí)態(tài)的句子，從句是由if引導(dǎo)的一般現(xiàn)在時(shí)態(tài)的句子，符合主將從現(xiàn)的法則。）2.主句是含有情態(tài)動(dòng)詞may/might/can/must/should等句子。例如：Ifyouwanttoloseweight,youmusteatlessbread.如果你想減肥，你必須少吃面包。（主句中含有情態(tài)動(dòng)詞must，所以if引導(dǎo)的條件狀語(yǔ)從句要用一般現(xiàn)在時(shí)態(tài)。）3.主句是祈使句例如：Ifyouarenotstrongenough,pleasedon'ttakepartinsuchanactivity.如果你不夠強(qiáng)壯，請(qǐng)不要參加這種活動(dòng)。（：主句是一個(gè)Do型的祈使句，所以根據(jù)原則，if從句要用一般現(xiàn)在時(shí)態(tài)。——不清楚Do型祈使句的小伙伴可以查看冉老師歷史發(fā)文記錄）三.句型的相互轉(zhuǎn)換借助“祈使句+and/or+句子（一般將來(lái)時(shí)結(jié)構(gòu)）”這一句型來(lái)轉(zhuǎn)換，在句子中，and表示順承，or表示“否則”。例如：Ifyouworkhard,you'llsuccess.如果你努力學(xué)習(xí)，你將會(huì)成功。=workhard，andyou'llsuccess.努力學(xué)習(xí)，那么你將會(huì)成功。=Workhardoryouwon'tsuccess.努力學(xué)習(xí)，否則你不會(huì)成功。（同學(xué)們注意and和or的翻譯，在日常寫作中也可以和if引導(dǎo)的條件狀語(yǔ)從句相互轉(zhuǎn)換，增加自己文章的看點(diǎn)。）

2.借助without/with來(lái)轉(zhuǎn)換條件狀語(yǔ)從句。例如：Ifthereisnowater,fishwilldie.如果沒(méi)有水，那么魚就會(huì)死。=Fishwilldiewithoutwater.沒(méi)有水，魚將會(huì)死。（補(bǔ)充——without是介詞，所以在學(xué)習(xí)中同學(xué)們注意介詞后面要加ing）

Ifyouhelpme，I'llfinishthework.如果你幫助我，我將會(huì)完成這項(xiàng)任務(wù)（主將從現(xiàn)）=withyourhelp,I'llfinishtheworksoon.找你的幫助下，我將會(huì)完成這項(xiàng)任務(wù).（第一個(gè)句子采用的是if引導(dǎo)的條件狀語(yǔ)從句，且遵循“主將從現(xiàn)”的原則。第二個(gè)借助的是介詞with，兩句都含有對(duì)將來(lái)事情推測(cè)的含義。）

練習(xí)答案（

）1.We'dbetterhurry______itisgettingdark.A.and

B.but

C.as

D.unless

（

）2.Ididn'tmanagetodoit_____youhadexplainedhow.A.until

B.unless

C.when

D.before

（

）3._____hecomes,wewon'tbeabletogo.A.Without

B.Unless

C.Except

D.Even

（

）4.Ihurried_____Iwouldn'tbelateforclass.A.since

B.sothat

C.asif

D.unless

（

）5._____Icatchacold,Ihavepaininmyback.A.Everytime

B.Though

C.Even

D.Where

（

）6.What'sthematter_____theystillhaven'tansweredthetelegram?A.when

B.that

C.though

D.however

（

）7.Bringitnearer_____Imayseeitbetter.A.although

B.eventhough

C.sothat

D.since

（

）8.YoumayarriveinBeijingearly_____youmindtakingthenighttrain.A.that

B.though

C.unless

D.if

（

）9.Helenlistenedcarefully_____shemightdiscoverexactlywhatsheneeded.A.inthat

B.inorderthat

C.incase

D.eventhough

（

）10.Morepeoplewilleatoutinrestaurants_____theydotoday.A.than

B.when

C.while

D.as

（

）11._____hardshetries,shecanhardlyavoidmakingmistakesinherhomework.A.Much

B.However

C.As

D.Although

（

）12.Poor_____itmaybe,thereisnoplacelikehome,_____youmaygo.A.as;wherever

B.though;whenever

C.inspiteof;when

D.that;wherever

（

）13.Thechildwas__immediatelyaftersupper.A.enoughtiredtogotobed

B.tootiredtogotobedC.sotiredthathewenttobed

D.verytired,hewenttobed

（

）14.Thehistoryofnursing__thehistoryofman.A.asoldas

B.isoldthan

C.thatisasoldas

D.isasoldas

（

）15._____borninChicago,theauthorwasfamousforhisstoriesaboutNewYork.A.Since

B.Once

C.When

D.Although

（

）16._____westoodatthetopofthebuilding,thepeoplebelowwerehardlyvisible.

A.As

B.Although

C.Unless

D.Inspiteof

（

）17.ScarcelywasGeorgeWashingtoninhisteens_____hisfatherdied.A.than

B.as

C.while

D.when

（

）18._____Davidgoes,heiswelcome.A.Whichever

B.However

C.Wherever

D.Whatever

（

）19.Thehousestood_____therehadbeenarock.

A.which

B.atwhich

C.when

D.where

（

）20.Small_____itis,thepenisamostusefultool.A.because

B.so

C.if

D.as

（

）21.Afterthenewtechniquewasintroduced,thefactoryproduced

carsin1988astheyearbefore.A.astwicemany

B.asmanytwice

C.twiceasmany

D.twicemanyas

（

）22.Thepianointheothershopwillbe_____,but_____.A.cheaper;notasbetter

B.morecheap;notasbetterC.cheaper;notasgood

D.morecheap;notasgood

（

）23.Johnplaysfootball_____,ifnotbetterthan,David.A.aswell

B.aswellas

C.sowell

D.sowellas

（

）24.Althoughheisconsideredagreatwriter,A.hisworksarenotwidelyread

B.buthisworksarenotwidelyreadC.howeverhisworksarenotwidelyread

D.stillhisworksarenotwidelyread

（

）25.___thedaywenton,theweathergotworse.A.With

B.Since

C.While

D.As

（

）26.—Whatwasthepartylike?

—Wonderful.It'syears_____Ienjoyedmyselfsomuch.A.after

B.when

C.before

D.since

（

）27.Itwasnot_____shetookoffherdarkglasses_____Irealizedshewasafamousfilmstar.A.when;that

B.until;that

C.until;when

D.when;then

（

）28.Ifweworkwithastrongwill,wecanovercomeanydifficulty,_____greatitis.A.what

B.how

C.however

D.whatever（

）29.Afterthewar,anewschoolbuildingwasputup_____therehadoncebeenatheat