before和until的用法和区别.pptVIP

.;1. My friends walked me to the bus stop and waited with me _______ the bus arrived. （before ；until ）;I waited _______ he came back. 我一直等到他回来。 ;until before 区别 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，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： 一、在下列情况下，两者可互换用，但含义略有不同。before表示“在……之前”的意思，强 调时间先后关系；而until表示“直到……才”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间。 ;1.主句为否定式终止性谓语动词。常见的动词是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.主句为肯定式、延续性谓语词，这类动词用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、在下列情况下，用before不用until。 1.主句这肯定式、终止性谓语动词，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： (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. ;4.表“与其说……倒不如”，“与其……毋宁……”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.; 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、否定都可以，但意义完全不同。肯定表动作终止，而否定表动作开始。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问题。;2.not…until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until。 例如： (1)It was not until