before和until的用法及區(qū)別.ppt

.,.,before 與 until,1. My friends walked me to the bus stop and waited with me _ the bus arrived. （before ；until ）,此題不能選before，因?yàn)闀r(shí)態(tài)不對(duì)。如果把walked和waited改成過去完成式had walked和had waited就可以選before。before的使用一般有強(qiáng)烈的時(shí)態(tài)要求而until一般沒有時(shí)態(tài)要求,until,I waited _ he came back. 我一直等到他回來。,I didnt leave _ he came back . 直到他回來我才走,I can only give you an answer _ I think it over.,until,until,before,until before 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問題?，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。,1.主句為否定式終止性謂語動(dòng)詞。常見的動(dòng)詞是open, start, leave, arrive, finish, stop等。 例如： (1)The noise of the street didnt stop until/before it was midnight. (2)The children wont come back until/before it is dark. (3)I didnt leave the lovely boy until/before his mother came home.,2.主句為肯定式、延續(xù)性謂語詞，這類動(dòng)詞用stand, stay, talk, be, wait等。 例如： (1)He lived with his parents until/before he graduated from school. (2)I will wait until/before he comes to my help. (3)I shall stay here until/before you come back.,二、在下列情況下，用before不用until。 1.主句這肯定式、終止性謂語動(dòng)詞，只用before。例： (1)He fell asleep before I could take off his clothes. (2)We arrived there before it started to rain. (3)The holiday came to the end before I knew it. (4)He almost knocked me down before he saw me.,2.主句謂語動(dòng)詞強(qiáng)調(diào)動(dòng)詞的遲緩性，只用before，常伴有時(shí)間段狀語或時(shí)間段暗示。例： (1)It was quite some time before he found the elephant at all. (2)We had walked a long way before we found some water. (3)We had sailed for two days before we saw the land. (4)The fire lasted about four hours before the firefighters could control it.,(5)It was midnight before my brother came home. (6)It was three months before they met again.,3.如果強(qiáng)調(diào)從句謂語動(dòng)作未發(fā)生，就發(fā)生主句謂語動(dòng)作，只用before。常譯為“未及”，“不”或“不等就”。例： (1)We can leave early in the morning before it gets too hot. (2)I must write it down before I forget it. (3)We do want to buy something now before prices go up.,4.表“與其說倒不如”，“與其毋寧”只用before。 例： (1)I would give up my job before Id agree to be dismissed. (2)He will die of hunger before he will steal.,5.在某些特定句型中用before。例如： (1)It was not long before the whole country rose up. (2)It will probably not be long before they understand each other.,三、下列情況一般區(qū)別用until。 1.主句是持續(xù)性謂語動(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)作開始。例如： (1)We discussed the problem until/before he came back.我們一直討論到他回來。 (2)We didnt discuss the problem until he came back.我們一直等到他回來后才討論問題。,2.notuntil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)It was not until he told me that I knew it. (2)It was not until he finished his homework that he went home.,They were taking a p