一、表示“在……之后……才”。副词“才”在汉语中强调某事发生得晚或慢。如果在含有before从句的复合句中，强调从句动作发生得晚或慢时，就可以应用这种译法。

The American Civil War lasted four years _______ the North won in the end.(2005广东)

A. after                    B. before                C. when           D. then

二、表示“……还没来得及……就……”。目的在于强调从句动作发生之前，主句动作已发生。

—Why didn't you tell him about the meeting? (2006四川卷)

       — He rushed out of the room _________ I could say a word.

            A. before           B. until            C. when         D. after

三、表示“在……之前就……”。这时主句与before从句中的两个动作按时间先后依次发生。

It was evening______ we reached the little town of Winchester. （2004天津）

A. that            B. until           C. since          D. before

四、表示“趁……”，“等到……”，或 “没等……就…… ”等。

He made a mistake, but then he corrected the situation _____ it got worse.（2003北京）

A. until        B. when           C. before                  D. as

五、用于句型“It + will/would be + 时间段 + before...”句型中，表示“要过多久才…”，也可用于“It + may be + 时间段 + before...”，表示“也许要过多久才……”。其否定形式“It will/would not be +时间段+ before…”表示“不久就……，过不了多久就……”。

（1）The field research will take John and Paul about five months; it will be a long time _____ we meet them again.（2007安徽卷）

 A. after          B. before         C. since           D. when

（2）—How long do you think it will be ______China sends a manned spacesship to the moon? （2006福建卷）

—Perhaps two or three years.

A. when           B. until         C. that        D. before

（3）It ________ long before we _______ the result of the experiment.( 上海春招2002)

A. will not be...will know         B. is...will know

C. will not be...know                  D. is...know

(4) Scientists say it may be five or six years_________ it is possible to test this medicine on human patients. （2004福建）

A. since          B. after          C. before         D. when

六、用于句型 “it was +时间段+ before …” 表示 “过了（多长时间）才……”。其否定形式“ it was not +时间段+ before …” 意为“不久就……”, “没过（多长时间）就……”。

It was some time ___________we realized the truth. （2005山东）

  A. when       B. until         C. since                D. before

七、和hardly连用，表示“刚一……就……”。该结构主句常用过去完成时，当hardly位于句首时，要用倒装语序，例如：

 I had hardly sat down before the telephone rang.

Hardly had I sat down before the telephone rang.

八、和其它相似句型的区别

有时候before引导的时间状语从句与since，when引导的时间状语从句在下列结构中较相似，容易混淆。

“It be +时间段 + since引导的时间状语从句”表示“自从……已经有多长时间了”。主句用一般现在时或现在完成时。

“It be +时间点+when引导的时间状语从句”表示“某个动作发生时，是某个时间”。主句谓语动词可以是一般过去时，也可以是一般将来时。

（1）It is almost five years     we saw each other last time. （2005北京春）

A. before         B. since         C. after            D. when

（2）— Did Jack come back early last night? （2005福建）

— Yes. It was not yet eight o’ clock________ he arrived home.

A. before              B. when        C. that             D. until

九、before long和long before的区别

before long意为“不久，很快”（其中before是介词，long是名词），常在句中作状语，多与动词的过去时或将来时连用。例如：

The work will be finished before long. 工作不久就会完成。

Before long he had to move on again. 不久，他被迫再次迁移。

long before意为“很久以前”（其中long是副词。long before单独使用时， before是介词；long before后接从句时，before是连词。）这个词组常与过去时或过去完成时连用，跟从句时也可用在一般现在时的句子中。例如：

She said that she had heard of it long before. 她说她早就听说过此事。

It will be long before he arrives. 还要等很久他才能到达。

巩固练习

一、选词填空

1. before long/long before

(1) __________he went to America.

(2) I hope to see you ____________.

(3) She said she had read the novel ______________.

(4) I had not waited ______________ she came.

5）It was not ____________he got to know it.

2. before/since/when

(1) It was four 0’clock _______ they arrived at the town.

(2) It has been 3 years__________ his brother went abroad for further study.

(3) It will be more than a week __________ his mother recovers from the disease.

二、翻译下列句子

1. 不等我说一句话，她就冲出了房间。

2. 他叔叔五年后才能回来。

3. 不久之后，敌人就被赶走了。

4. 他们不久就会互相了解的。

5. 他们正在考虑趁房价未涨时把房子买下来。

1. She had stormed out of the room before I could say a word

2. It will be five years before his uncle comes back.

3. It was not long before the enemy was driven out of their country.

4. It won’t be long before they understand each other.

5. They are thinking of buying the house before the prices go up.

四、单项选择

1. —Why didn't you tell him about the meeting ?

     — He rushed out of the room _________  I could say a word.

     A. before           B. until            C. when       D. after

2. —How long do you think it will be ______China sends a manned spaceship to the moon?

—Perhaps two or three years.

A. when               B. until          C. that         D. before

3 .He was told that it would be at least three more months   he could recover and return to work.

  A. when        B. before       C. since    D. that

4. Several weeks had gone by______ I realized the painting was missing.

A. as              B. before          C. since           D. when

5. Scientists say it may be five or six years_________ it is possible to test this medicine on human patients.

A. since          B. after          C. before         D. when

6. The American Civil War lasted four years ________ the North won in the end.

   A. after      B. before    C. when        D. then

7. That was really a splendid evening. It’s years ______ I enjoyed myself so much.

    A. when         B. that             C. before       D. since

8. It was some time ___________we realized the truth.

   A. when         B. until         C. since        D. before

9 .He was told that it would be at least three more months   he could recover and return to work.

  A. when        B. before       C. since    D. that

10. —Where’s that report?

   —I brought it to you ____you were in Mr. Black’s office yesterday.

A. if                    B. when   C. because             D. before

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