as的用法

as这个词看似简单，但用法却是很多的，对它的正确理解关系到英语应用能力的提高，因此我们有必要对其用法和搭配进行详细阐述。

一、as作介词

1. 区别as和like

as作为介词时，可以表示“像……”，这时它可以和like互用；as还可以表示“以……身份”或“作为……”，“当作……”，但like不能。

e.g. I) They lived and fought among the people as “fish in water”. (as相当于like)

II) As a scientist, he was dedicated to (致力于) the truth. (这里不可以用like)

II) They talked as old friends. (他们确乎是老朋友。)

à They talked like old friends. (他们像老朋友一样。)

2. as引导的介词短语在句中可以充当：

a) 宾语补足语

e.g. I) She spoke of me as her dearest friend.

II) The plan struck me as very much worthwhile.

III) You mustn’t think of me as (being) unhappy.

b) 主语补足语

 e.g. I) She is well-known as being very cheerful.

II) He is sometimes portrayed as belonging to another century.

III) That picture is looked upon as very valuable.

常用于这类结构的动词有：accept, consider, describe, elect, interpret (理解), look upon, perceive, recognize, refer to, regard, see, strike, take, think of, treat, view等等。

二、as作连词

1. 作“当……的时候”,引导时间状语从句。注意与when、 while的用法区别。

A.  when作"当……的时候"解,可以指较短的(一点)时间,也可指一段时间。

e.g. I)When he was at college, he could speak several foreign languages.

II) When the clock struck twelve, all the lights in the street went out. 

B. while常表示一段较长的时间或一个过程,强调主句谓语动词与从句谓语动词同时发生。

e.g. Work while you work. Play while you play.

C. 但属下列情形时,只用as, 而不用when或while。

1) 用于表示同一个人的两种动作交替进行,指“一边……,一边……”。

e.g.I)The girl dances as she sings on the stage. 

II) He looked behind from time to time as he went forward.

2)表示两个同步发展的动作或行为,译为“随着……”。

e.g. I) As time went on / by, she became more and more worried. 

II) As children get older, they become more and more interested in the things

around them. 

3)表示两个短促行为或事件几乎同时发生。

e.g. I) I thought of it just as you opened your mouth. 

II) Just as the flying worm hit her face, she gave a loud cry.

4) 后接名词表示某一年龄段时,用as。

e.g. As a young man, he was active in sports. 

2. as=since, 作“既然”、“由于”解,引导原因状语从句,常用来表示已为人们所知或显而易见的原因或理由。

e.g. I)As / Since you’re not feeling well, you may stay at home.

II) As he wasn't ready in time, we went without him.

3. as=in the way that, 作“像”、“按照……的方式”解，引导方式状语从句。

e.g. I)He speaks English as Americans do.

II) Remember, you must do everything as I do.

4. 用于as...as...或not so/ as...as...中,前一个as是副词,后一个as是连词，引导比较状语从句。

e.g. I) They helped the old man as often as possible. 

II) I don’t speak English so / as well as he does. 

5. 作“虽然”、“尽管”解,引导让步状语从句。常用倒装语序,即adj. /adv. / n.+ as +主语+谓语+主句。

e.g. I) Tired as they were, they walked on.

II) Child as he is, he knows a lot. (child前不用冠词)

6．as引导类比从句，与so 连用，表示“正如……所以……”。

e.g. Just as French people enjoy their wine, so the British enjoy their beer.

如同法国人喜欢他们自产的葡萄酒一样，英国人喜欢他们自产的啤酒。

三、as作副词

1．表示同等程度、质量、数量等，作“一样地……”解释。

e.g. I) Steve runs fast, but I run just as fast.

史蒂夫跑的很快，但是我跑的和他一样快。

II) Tom has a lot of money, but I don’t have as much.

汤姆有很多的钱，而我的钱没有他多。

2．用在形容词或者-ed形式的过去分词前，相当于形容词或过去分词作定语，但as仍然保留其原来的词汇意义。

e.g. I) In the dead of night I was suddenly wakened by a cry as made by a wolf.

在寂静的黑夜里，我突然听到了一声如同狼嚎一样的叫声。

II) The old man began to describe the accident as seen through the eyes of a witness.

这位老人开始描述这一起事故，如同是一个证人亲眼目睹了一般。

四、作as作关系代词，引导定语从句，不仅可以代替一个名词，而且可以代替整个句子或一件事，通常译作 “正如这一点”，“如……一样”。

e.g. I) As is known to everybody, the moon travels around the earth once every month.

如同大家所知道的一样，月亮每月围绕地球旋转一次。

II) As has been said before, grammar is not a set of dead rules.

如同以前说过的一样，语法并不是一套死规则。

III) Such a clever girl as she can learn anything quickly.

像她这样聪明的女孩子学任何东西都很快。

IV) It was absolutely bad manners to get into people’s room without knocking, as quite a few young people are doing every day.

不敲门就进入别人的房间绝对是不文明的行为，现在很多年轻人每天都这么干。

五、as构成的固定词组

1．as可以构成介词词组：

as against（与……相比）；as compared with（与……对比）；as for / to（至于，关于）；as from / of（自……起）；as a result of（由于……的结果）；as regards（至于）；

e.g. I) The output amounts to ten thousand dollars as against eight thousand last year.

和去年八千美元的产量相比，今年的产量达到了一万美元。

II) There is no doubt as to who will be elected.

至于谁会当选，这是毫无疑问的事。

III) As a result of your carelessness, the whole project should be put off at least one month.

由于你的粗心，整个计划将要被推迟至少一个月。

2．as可以构成副词词组：

as above（如上）；as a matter of fact（事实上）；as a whole（就整体来说）；as follows（如下）；as good as（和……几乎一样，实际等于）；as such（照其资格，其本身）；such / so … as to（这样的……以至于……）；as yet（尚，至今还）（用于否定句）；as well（也）；

e.g. I) As a matter of fact, he didn’t have any interest in the project.

事实上，他对这个项目一点兴趣都没有。

II) I am not so foolish as to make such a promise.

我还没有愚蠢到会许下这样的承诺的地步。

III) We are as good as ruined.

我们几乎要崩溃了。

3．as构成词组作关系代词：

as … go（就……一般情况来说）；as it is / was（事实上，按现状）；as it were（好像是）；

e.g. I) He is quite good, as boys go. 就一般男孩子而言，他已经很好了。

II) I thought conditions would get better, but as it was, they were getting worse.

我以为情况会好转，但事实上，却是越来越糟糕。

4．as可以构成连词词组：

according as（根据，按照……而）；in as (so) far as（根据……程度）；

e.g. I) You may go or stay, according as you decide.

你可以自己决定是去还是留。

II）In as (so) far as we have known about the matter, we can make a decision after the meeting.   就我们对这件事情的了解程度，我们可以在会后作出一个决定。