巧辨before和until

在日常英語教學中，我們遇到學生問這樣的一些問題：1.He will spend six hours at his desk____he finishes his composition.A.before B.until C.after D.when

2.The bike hit the tree____I could get off.A.when B.before C.while D.until

3.I knocked at the door for more than five minutes____Mrs white answered it.A.until B.when C.after D.before

4.It was____yesterday____be____the secret.A.not until;that;knew B.until;when;knewC.not before;that;found D.before;that;didn't find

怎樣才能清楚地解釋其選擇的原因，這就涉及到until與before的區別問題。實際上，只要我們把握住兩者使用時本身的含義及主句動詞是終止性的，還是延續性的，肯定式，還是否定式兩大點，就能容易地解決這類問題。

現詳細闡明如下：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 調時間先后關系;而until表示“直到……才”的意思，主句是肯定句則表示主句動作的終止時間;主句是否定句則強調主句動作的起始時間。

1.主句為否定式終止性謂語動詞。常見的動詞open,start,leave,arrive,finish, stop等。

(1)The noise of the street didn't stop until/before it was midnight.

(2)The children won't come back until/before it is dark.

(3)I didn't leave the lovely boy until/before his mother came home.

2.主句為肯定式、延續性謂語詞，這類動詞用stand,stay,talk,be,wait等。

(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 heer until/before you come back.

二、在下列情況下，用before不用until。1.主句這肯定式、終止性謂語動詞，只用before。

(1)He fell asleep before I could take off his clothes.

(2)We arrived there before it atarted to rain.

(3)The holiday came to the end befor I knew it.

(4)He almost knocked me down before he saw me.

2.主句謂語動詞強調動詞的遲緩性，只用before，常伴有時間段狀語或時間段暗示。

(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 countrol it.

(5)It was midnight before my brother came home.

3.如果強調從句謂語動作未發生，就發生主句謂語動作，只用before。常譯為“未及”，“不”或“不等……就”。

(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。

(1)I would give up my job before I'd 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。

(1)It was not long before the whole country rose up.

(2)It will probably not be long before they understand each other.

三、下列情況一般區別用until1.主句是持續性謂語動詞時，肯定、否定都可以，但意義完全不同�？隙ū韯幼鹘K止，而否定表動作開始。

(1)We discussed the problem until/before he came back.我們一直討論到他回來。

(2)We didn't discuss the problem until he came back.我們一直等到他回來后才討論問題。

2.not…until句型盡管在某些情況下可與before互換用，但在強調句中一般仍用until。

(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.

綜上所述，前面的4條選擇題中，第1、3題強調動作發生的遲緩性應選before。第2題表動作未及發生就發生主句動作也應選before。第4題為強調句應選A項。

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