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英語條件句及其表達(dá)方式詳解英語中的條件句種類很多,可用來表達(dá)建議、想法、結(jié)果和趨勢等，其出現(xiàn)頻率很高。在英語學(xué)習(xí)中，正確理解和抓住說話者所要表達(dá)的真實意圖至為重要。下面介紹幾種條件句及其不同的表達(dá)方式。

一、不同的條件句

1．真實條件句(realconditions)。用于陳述句，表假設(shè)的情況可能發(fā)生，其表達(dá)的意思直接而明顯。

Ifhecomes,Ishallbesurprised.

Ifyouareenjoyingtheparty,don’tgohomeyet.

Ifyouhavedoneyourhomework,giveittome.

2．非真實條件句(unrealconditions)。非真實條件句分為三種情況：(1)與現(xiàn)在情況不符,(2)與過去情況不符,（3)與將來情況不符。非真實條件句是建立在與事實相反，或很難成為現(xiàn)實的假設(shè)基礎(chǔ)上，其表達(dá)的意思是間接而含蓄的，表示假設(shè)的或?qū)嶋H可能性不大的情況。

Ifyouateless,youwouldloseweight.(可惜現(xiàn)在并未少吃)

Ifyouhadtakenanumbrella,youwouldn’thavebeensowet.（可惜那時沒帶傘）

Whatwouldyoudoifwarweretobreakout?(好在戰(zhàn)爭并不會爆發(fā))

3．虛擬條件句（subjunctiveconditions)。虛擬條件句的從句部分如果含有were,should或had,可將if省略，再把這些詞移到從句句首,實行倒裝，構(gòu)成不出現(xiàn)條件詞的虛擬條件句。

Weretheyherenow,theycouldhelpus.

Hadyoucomeearlier,youwouldhavemethim.

Shoulditrain,cropswouldbesaved.

4．混合條件句(compositeconditions)，也叫錯綜時間條件句。即主句和從句的時態(tài)不相同，動作發(fā)生在不同的時間，主、從句謂語的虛擬語氣形式因時間不同而不同。

IfJohnsonhadn’tbeenwarnedofthedangerlastnight,hewouldn’tdoeverythingsocarefully.

Ifithadrainedlastnight,itwouldbecoldtoday.

HadPaulreceivedsixmorevotesinthelastelection,hewouldbeourchairmannow.

5．含蓄虛擬條件句(complicitconditions),即條件句的簡略形式。含蓄虛擬條件句指句中沒有明顯的虛擬條件句，而是利用其他手段(詞匯手段、句子結(jié)構(gòu)、上下文等)來暗示存在虛擬條件。

Wecouldhavedonebetterundermorefavorableconditions.

Butforhishelp,Ishouldn’thavesucceeded.Intheabsenceofmathematics,sciencewouldnotexist.

Marycouldn’thavereceivedmyletter,otherwise,shewouldhaverepliedbeforenow.

6．開放式條件句（openconditions)。即省略should的條件句。

Ifanypersonbeguiltyofacrime,hewouldbeprosecuted.

Whethersheberightorwrong,shewillhavemyunansweringsupport.

二、條件句的表達(dá)方式

1．用連詞表達(dá)條件。最常見的連詞有if,unless,aslongas,onlyif,or,but,otherwise等。

Ifitweren’tforhim,wewouldhavegoneastray.

Ifyouwanttobeextracautious,askyourcreditcardcompanytoissueyouaonetime-usecreditcard.

Youmayborrowmybooksolongasyoukeepitclean.

Imighthavegivenyoumorehelp,butIwasbusy.

Onlyiftheredlightcomesonisthereanydangerahead.

2．用非謂語動詞形式表達(dá)條件

（1）V-ing/V-ed/V-baseform+that(clause)表達(dá)條件

Assumingthatasite’ssecure,yourcreditcardisthesafestwaytopay.

Supposing/Supposethatitrains,wecantakeshelterinthestation.

GiventhatIhavethemeansenough,I’llmaketheattempt.

Granted/Grantingthatheisnotbrilliant,heatleastworkshard.

(2)分詞及獨立主格結(jié)構(gòu)表達(dá)條件

Havingknownintime,wemighthavepreventedtheaccident.

Borntendaysearlier,theboycouldhaveseenhislatefather.

Allthingsconsidered,thepricewouldbereasonable.

(3)動詞不定式表達(dá)條件

Shewouldbestupidnottoaccepthisinvitation.

Itwouldbeamistakenottoadoptacorrectattitudetowardsothers’criticism.

TohearhimspeakFrench,youwouldtakehimforanEnglishman.

3．介詞短語及介詞短語+從句表達(dá)條件

I’llletyougoonconditionthatyouneverwastemoney.Youshouldinsureyourhouseincasethere’safire.

類似的結(jié)構(gòu)還有forfearthat/of,inorderthat,without,butthat/for...

Butforthestorm,weshouldhavearrivedearlier.

Wecouldhavedonebetterundermorefavorableconditions.

4．定語從句表達(dá)條件

Amanwhostoppeddrinkingwaterwouldbedeadinabout7days.

Anyonewhohadbeeninyourpositionwouldhavedonethesame.

Anation,whichstoppedworking,wouldbedeadinafortnight.

5．助動詞放句首表達(dá)條件

Shouldanyvisitorscome,Iwould/willsayyouarenotin.

Hadweenoughtime,thingswouldbeeasy.

HadIknownaboutit,Iwouldhavetoldyou.

6．形容詞和副詞的比較級形式表達(dá)條件

Amoreresponsiblepersonwouldn’thavelefttheworkhalfdone.

Alessconscientiousmanwouldn’thavetriedsohardtogetthejobdone.

7．祈使句+and或or引出的陳述句表達(dá)條件

Dothatagainandyou’llbeintrouble.

Givehimaninch,andhe’lltakeafoot.

Gobytrainandyou’llgettheremorequickly.

Takecareoryou’llfall.

Don’teatsomuchchocolateoryou’llfeelsick.

Hide,orelsehe’llcatchyou.

Doasyouaretold,otherwiseyou’llfeelsorry.

8．在正式文體中，謂語可用動詞原形表達(dá)條件

Godblessyou!

Allmagnetsbehavethesame,betheylargeorsmall.

She’llbesixteenyearsold,comeMay.

Ifthatbeso,weshalltakeactionatonce.

9．情態(tài)動詞的完成式表達(dá)條件

Ishouldhavecalledtomakeanairlinereservation,butIdidn’t.