..before與until1精選課件1.Myfriendswalkedmetothebusstopandwaitedwithme_______thebusarrived.（before；until）此題不能選before，因?yàn)闀r(shí)態(tài)不對(duì)。如果把walked和waited改成過(guò)去完成式hadwalked和hadwaited就可以選before。before的使用一般有強(qiáng)烈的時(shí)態(tài)要求而until一般沒(méi)有時(shí)態(tài)要求until2精選課件Iwaited_______hecameback.我一直等到他回來(lái)。Ididn'tleave______hecameback.直到他回來(lái)我才走Icanonlygiveyouananswer______Ithinkitover.untiluntilbefore3精選課件untilbefore區(qū)別實(shí)際上，只要我們把握住兩者使用時(shí)本身的含義及主句動(dòng)詞是終止性的，還是延續(xù)性的，肯定式，還是否定式兩大點(diǎn)，就能容易地解決這類(lèi)問(wèn)題?，F(xiàn)詳細(xì)闡明如下：

一、在下列情況下，兩者可互換用，但含義略有不同。before表示“在……之前”的意思，強(qiáng)調(diào)時(shí)間先后關(guān)系；而until表示“直到……才”的意思，主句是肯定句則表示主句動(dòng)作的終止時(shí)間；主句是否定句則強(qiáng)調(diào)主句動(dòng)作的起始時(shí)間。

4精選課件1.主句為否定式終止性謂語(yǔ)動(dòng)詞。常見(jiàn)的動(dòng)詞是open,start,leave,arrive,finish,stop等。

例如：

(1)Thenoiseofthestreetdidn'tstopuntil/beforeitwasmidnight.

(2)Thechildrenwon'tcomebackuntil/beforeitisdark.

(3)Ididn'tleavethelovelyboyuntil/beforehismothercamehome.5精選課件2.主句為肯定式、延續(xù)性謂語(yǔ)詞，這類(lèi)動(dòng)詞用stand,stay,talk,be,wait等。例如：

(1)Helivedwithhisparentsuntil/beforehegraduatedfromschool.

(2)Iwillwaituntil/beforehecomestomyhelp.

(3)Ishallstayhereuntil/beforeyoucomeback.6精選課件二、在下列情況下，用before不用until。

1.主句這肯定式、終止性謂語(yǔ)動(dòng)詞，只用before。例：

(1)HefellasleepbeforeIcouldtakeoffhisclothes.

(2)Wearrivedtherebeforeitstartedtorain.

(3)TheholidaycametotheendbeforeIknewit.

(4)Healmostknockedmedownbeforehesawme.7精選課件2.主句謂語(yǔ)動(dòng)詞強(qiáng)調(diào)動(dòng)詞的遲緩性，只用before，常伴有時(shí)間段狀語(yǔ)或時(shí)間段暗示。例：

(1)Itwasquitesometimebeforehefoundtheelephantatall.

(2)Wehadwalkedalongwaybeforewefoundsomewater.

(3)Wehadsailedfortwodaysbeforewesawtheland.

(4)Thefirelastedaboutfourhoursbeforethefirefighterscouldcontrolit.

8精選課件(5)Itwasmidnightbeforemybrothercamehome.

(6)Itwasthreemonthsbeforetheymetagain.3.如果強(qiáng)調(diào)從句謂語(yǔ)動(dòng)作未發(fā)生，就發(fā)生主句謂語(yǔ)動(dòng)作，只用before。常譯為“未及”，“不”或“不等……就”。例：(1)Wecanleaveearlyinthemorningbeforeitgetstoohot.

(2)ImustwriteitdownbeforeIforgetit.

(3)Wedowanttobuysomethingnowbeforepricesgoup.9精選課件4.表“與其說(shuō)……倒不如”，“與其……毋寧……”只用before。例：(1)IwouldgiveupmyjobbeforeI'dagreetobedismissed.(2)Hewilldieofhungerbeforehewillsteal.

5.在某些特定句型中用before。例如：(1)Itwasnotlongbeforethewholecountryroseup.(2)Itwillprobablynotbelongbeforetheyunderstandeachother.10精選課件

三、下列情況一般區(qū)別用until。1.主句是持續(xù)性謂語(yǔ)動(dòng)詞時(shí)，肯定、否定都可以，但意義完全不同?？隙ū韯?dòng)作終止，而否定表動(dòng)作開(kāi)始。例如：(1)Wediscussedtheproblemuntil/beforehecameback.我們一直討論到他回來(lái)。(2)Wedidn'tdiscusstheproblemuntilhecameback.我們一直等到他回來(lái)后才討論問(wèn)題。11精選課件2.not…until句型盡管在某些情況下可與before互換用，但在強(qiáng)調(diào)句中一般仍用until。例如：(1)ItwasnotuntilhetoldmethatIknewit.(2)Itwasnotuntilhefinishedhishomeworkthathewenthome.12精選課件Theyweretakingapeaceful