刘英琪

as 是高考的重要考点之一。由于它的词性复杂，所以它在不同的句子里拥有不同的意思。鉴于它的用法颇多，我认为我们很有必要弄清它的特点，以便牢牢掌握它的用法，从而做到在高考中不丢分。

用法一： as, when 以及while 的用法比较

as, when以及while 的相同点：

它们都可以作“当……的时候”讲，有时可以通用。例如：

Mother was worried because little Alice was ill, especially as / when / while Father was away in France.

as , when以及while 的不同点：

1. as除了表达“当……的时候”这个意思之外，还有“随着”的意思，而when 或while则没有。例如：

As the day went on, the weather got worse.一天天过去了，天气变得越来越糟。

2. as和when能引导定语从句，而while不能。

① As is known to us all, the moon travels round the sun once a month.

② Do you still remember one afternoon ten years ago when I came to your house and borrowed a necklace of yours?

3. while能做名词用，当“一会儿”，as和when 则不能；while也能用作并列连词，连接并列句，as和when 则不能。while和as能表达“尽管；虽然”的让步意义，when则不能。例如：

① She worked in a bank for a while before studying law. (while作名词用)

② While the Internet is of great help, I dont think its a good idea to spend too much time on it.（while表达让步意义）

③ In some places women are expected to earn money while men work at home and raise their children.（while连结并列句）

4. when能引导名词性从句，as和while则不能；when能表达“既然”，while则不能。when引导的时间状语从句的谓语动词的动作既可持续也可终止，而while引导的时间状语从句中的谓语动词则只能持续，不可终止。例如：

① When the Olympic Games will be held is still unknown.

② How can you expect to learn anything when （既然） you never listen?

③ When (不可用while代替) I stepped into the classroom, I found him reading a novel.

④ He fell asleep while (when) he was doing his homework.

用法二： as, because, since, for 的用法比较

从语气上看， as比for语气重,但是比because和since的语气又弱。其中because,since, as为从属连词，引导原因状语从句，而for为并列连词，连接并列句。

because表示直接原因，常用于回答why的问题，一般放在主句之后，这时主句和从句之间没有逗号，若放在主句之前时，要用逗号和主句分开。但是若用在否定的主句后，而其前面没有逗号时，则表达“不是因为……而干了某事”；若有逗号，否定词否定主句，不否定从句。例如：

① We stayed at home because it rained.

② Because I dont complain, people think I am satisfied.

③ I didnt go because I was afraid. 我不是因为害怕而去的。

④ I didnt go, because I was afraid. 因为我害怕，所以没有去。

since“因为；既然”，表意侧重于主句，从句表示显然的或稍加分析后可推断出来的双方都已经知道的原因。一般放在主句之前，用逗号和主句分开。不能回答why引导的疑问句。例如：

Since everybody is here, lets begin.既然大家都到了，我们开始吧！

as“由于；鉴于”，表意主从并重，它表示双方已知道的原因；和since 一样，不回答why引导的疑问句。一般用在句首，用逗号和主句分开。例如：

As he wasnt ready in time, we went without him.

for “因为；由于”，表明附加或推断的原因，它所提供的原因是一种补充性的说明，引导的分句前常有逗号，for分句不能放在句首。例如：

He must be ill, for he is absent today.

用法三： as, although以及though的用法比较

当as 用作连词引导让步状语从句时，它和although以及though的用法完全不同。as须用于倒装结构中；though即可用于倒装结构中，也可不用于倒装结构中，而although则不能用于倒装结构中。当as引导的让步状语从句倒装时，又不同于我们通常所说的倒装，它所在的句子的主语和谓语的词序不变。它的倒装共分为四类：单数可数名词提前类；形容词提前类；副词提前类和动词提前类。

⑴ 单数可数名词提前时，不定冠词通常省略，其它词序不变。例如：

___________, he talks a lot about his favourite singers after class.（2005重庆卷）

A. A quiet student as he may be

B. Quiet student as he may be

C. Be a quiet student as he may

D. Quiet as he may be a student

⑵ 形容词提前时把形容词放在as之前，其它词序不变。

________________ , his idea was accepted by all the people at the meeting.（2007重庆卷）

A. Strange as might it sound

B. As it might sound strange

C. As strange it might sound

D. Strange as it might sound

⑶ 副词提前

Much as I like you, I couldnt live with you. （much as = although）

Much as I would like to stay, I really must go home.

⑷ 动词提前时，把动词放在as之前，其它词序不变。

________________, Carolina couldnt get the door open.(2005广东卷)

A. Try as he might

B. As she might try

C. She might as try

D. Might she as try

用法四： as 和like的用法比较

在谈到人、事物或动作彼此有相同点或共同点时，使用as 和like均可。但是它们的词性不同。like是介词，用在名词和代词之前；as是连词，用于分句之前。但是在口语中，like往往可用作连词，当作as使用。例如：

Like me, she enjoys all kinds of music.(like不能用as代替)

She enjoys all kinds of music, as I do. （as 可以用like代替）

Nobody understands him like / as I do.

用法五： as 和which的用法比较

A. 在位置上的区别

as和which都能用来引导定语从句,但是它们既有区别，又有联系。当它们都引导非限定性定语从句时，都可代指整个句子。不同之处是，它们引导的非限制性定语从句的位置不同。which 引导的非限制性定语从句，只能放在主句之后，而as引导的非限制性定语从句，可放在主句之前，也可放在主句之后，还可以放在主句的主语和谓语之间。

⑴ as引导的非限制性定语从句放在主句的主语和谓语之间。例如：

① The beatles,________________many of you are old enough to remember, came from Liverpool.（2006天津卷）

A. what B. that C. how D. as

If knowledge is power, as Sir Francis Bacon wrote in 1597, then perhaps creativity can be described as the ability to use that power.（人教版高中第二册上第7页）

⑵ as引导的非限制性定语从句放在主句之前。例如：

③___________is often the case, we have worked out the production plan.(2004江苏卷)

A. Which B. When

C. What D. As

⑶ as引导的非限制性定语从句放在主句之后。例如：

Good friends_______________ happiness and value to life,________________ is known to us all.(2007年石家庄高中毕业班复习教学质量检测二)

A. add to; it B. add; it

C. add; as D. as; add to

⑷ which引导的非限制性定语从句代指整个句子时，只能放在主句之后。例如：

The road conditions there turned out to be very good, _____________- was more than we could expect. （2008全国卷Ⅱ）

A. it B. what

C. which D. that

As is often the case, he was late for school.(as不能用which替换，人教版高中第三册教师用书192页)

He came late for class today, which / as is often the case.

B. 在习惯用法上的区别

as 在引导限定性定语从句中，常见的习惯搭配有the same ... as和such ... as。例如：

Beijing was attacked by such a heavy terrible sandstorm________________few residents had ever experienced before.（2007黄冈市高三质量检测）

A. as B. which C. that D. what

Mrs. Black took the police back to ______________ place _____________-she witnessed the robbery.

A. the same; that B. the same; as

C. the same; where D. as the same; as

该题答案为C。这是因为尽管先行词place被the same 所修饰，但是place 在从句中不作主语或宾语，再者as是关系代词，所以要用where, 不用固定搭配the same ... as。

as在引导非限定性定语从句时，常见的习惯搭配有：as we all know, as is known to us all, as is often the case, as is usual with sb., as is said above, as is reported above, as is mentioned above, as could be expected等。

which在引导非限制性定语从句时，常和make或带有“使”的动词搭配，常译为“这使……”，相当于and it。

① Jim passed the driving test, __________ surprised everybody in the office.(2005浙江卷)

A. which B. that

C. this D. it

② Dorothy was always speaking highly of her role in the play, ______________ , of course, made the others unhappy.(2000年国卷)

A. who B. which

C. this D. what

C. 在主句和从句的内容上的区别

若从句和主句的内容不一致,或从句对主句的内容起反对、排斥、否定等作用时，多用which; 而as 只能用于主句和从句的内容一致时。例如：

She has married again, as was expected.

She has married again, which was unexpected.

用法六： as, so, neither, nor的用法比较

如同so一样, as 也可以放在句首,表示前面所说的肯定情况也适用于另一个人或物。其句型是as + 系动词（助动词或情态动词） + 主语。与so和as不同的是，neither 和nor 表示前面否定的内容也适用于另一个人或物。例如：

① Our eating habits have changed, as has our way of life, and the fuel we need for our body is also different.（人教版高一下册第三页）

② Shes unusually tall, as(so) are both her parents.（牛津高阶英汉双解词典68页）