before和until的用法及区别课件.ppt

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1、.1.My friends walked me to the bus stop and waited with me _ the bus arrived.（before；until）此题不能选此题不能选before，因为时态不对。如果把，因为时态不对。如果把walked和和waited改成过去完成式改成过去完成式had walked和和had waited就可以选就可以选before。before的使的使用一般有强烈的时态要求而用一般有强烈的时态要求而until一般没有时一般没有时态要求态要求 untilI waited _ he came back.我一直等到他回来。我一直等到他回来。I d

2、idnt leave _ he came back.直到他回来我才走直到他回来我才走 I can only give you an answer _ I think it over.untiluntilbeforeuntil before 区别区别实际上，只要我们把握住两者使用时本身的含义实际上，只要我们把握住两者使用时本身的含义及主句动词是终止性的，还是延续性的，肯定式，及主句动词是终止性的，还是延续性的，肯定式，还是否定式两大点，就能容易地解决这类问题。还是否定式两大点，就能容易地解决这类问题。现详细阐明如下：现详细阐明如下：一、在下列情况下，两者可互换用，但含义略一、在下列情况下，两者可

3、互换用，但含义略有不同。有不同。beforebefore表示表示“在在之前之前”的意思，强的意思，强 调时间先后关系；而调时间先后关系；而untiluntil表示表示“直到直到才才”的意思，主句是肯定句则表示主句动作的终的意思，主句是肯定句则表示主句动作的终 止时间；主句是否定句则强调主句动作的起始时止时间；主句是否定句则强调主句动作的起始时间。间。1.1.主句为否定式终止性谓语动词。常见的动主句为否定式终止性谓语动词。常见的动词是词是open,start,leave,arrive,finish,open,start,leave,arrive,finish,stop stop等。等。例如：例如

4、：(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.主句为肯定式、延续性谓语词，这类动主句为肯定式、延续性谓语词，这类动词用词用stand,stay,talk,be,waitstand,stay,talk,be,wait等。等。例如：例如：(1)He lived wit

5、h 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、二、在下列情况下，用在下列情况下，用before不用不用until。1.主句这肯定式、终止性谓语动词，只用主句这肯定式、终止性谓语动词，只用before。例：例：(1)He fell asleep before I could take off his clothes.(2)We arrived t

6、here 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.主句谓语动词强调动词的迟缓性，只用主句谓语动词强调动词的迟缓性，只用before，常伴有时间段状语或时间段暗示。例：，常伴有时间段状语或时间段暗示。例：(1)It was quite some time before he found the elephant at all.(2)We had walked a long way before

7、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.如果强调从句谓语动作未发生，就发生主如果强调从句谓语动作未发生，就发生主句谓语动作，只用句谓语动作，只用befo

8、re。常译为。常译为“未及未及”，“不不”或或“不等不等就就”。例：。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.表表“与其说与其说倒不如倒不如”，“与其与其毋宁毋宁”只用只用before。例：例：(1)I would give up my job before Id agree to be dismissed.(2)

9、He will die of hunger before he will steal.5.在某些特定句型中用在某些特定句型中用before。例如：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、下列情况一般区别用三、下列情况一般区别用until。1.主句是持续性谓语动词时，肯定、否定都主句是持续性谓语动词时，肯定、否定都可以，但意义完全不同。肯定表动作终止，而可以，但意义完全不同。肯定表动作终止，而

10、否定表动作开始。例如：否定表动作开始。例如：(1)We discussed the problem until/before he came back.我们一直讨论到我们一直讨论到他回来。他回来。(2)We didnt discuss the problem until he came back.我们一直等到他回来后才讨论我们一直等到他回来后才讨论问题。问题。2.notuntil句型尽管在某些情况下可与句型尽管在某些情况下可与before互换用，但在强调句中一般仍用互换用，但在强调句中一般仍用until。例如：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 peaceful walk in the woods_ three men sprang out from behind a bush and attacked them.A.until B.when C.before D.afterB