必会小升初英语语法As的用法知识点

 一、作副词，意为"相同地"，"同样地"。例如：

They don't have as many airplanes. 他们没有同样多的飞机。

二、作连词

1. 引导时间状语从句

as与when，while都是引导时间状语从句的从属连词，含义都是"当……的时候"。但它们有区别:

(1). when作"当……的时候"解，可以指较短的(一点)时间,也可指一段时间。从句的动作可以与主句的动作同时发生，也可以先于主句的动作发生。例如:

John was having his dinner when I saw him. 当我看到约翰的时候，他正在吃饭。

She can write only when the baby is asleep. 只有婴儿睡着的时候，她才能写作。

(2). 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或在从句动作过程中发生。例如:

We must strike while the iron is hot. 要趁热打铁。

While we were reading, the teacher came in. 我们正在读书的时候，老师走了进来。

(3). 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……"。例如:

The girl dances as she sings on the stage.那个女孩在舞台边唱歌边跳舞。

He looked behind from time to time as he went forward. 当他朝前走时，不时地向后看。

② 表示两个同步发展的动作或行为,译为"随着……"。例如:

As time went on / by, she became more and more worried. 随着时间的流逝，她变得越来越焦虑。

As he grew older, he became more intelligent. 随着他年龄的增长，他变得更有才智了。

③ 表示两个短促行为或事件几乎同时发生。例如:

I thought of it just as you opened your mouth. 恰好在你开口时，我想到了它。

Just as the flying worm hit her face, she gave a loud cry. 恰巧在飞虫撞到她脸上时，她大哭起来。

2. 引导原因状语从句

as，because，since都可以表示因果关系，连接原因状语从句，含义是"因为，由于"，但它们有区别：because表示的语气最强;as一般放在句首，语气较弱，较口语化;since常常用在书面语中，表示多为对方已知的、或稍加分析便可得知的原因，有时可译作"既然"。例如：

I do it because I like it. 我做这件事是因为我喜欢。

Since many of the customers work during the day, Billy has to collect the money at night. 因为许多顾客白天上班,所以毕利只好晚上去收钱。

As she has been ill perhaps she'll need some help. 她由于生病可能需要些帮助。

3. 引导让步状语从句

as与although (或though)，however (或no matter how)等都可以引导让步状语从句，含义是"虽然，尽管"，但它们有区别：although语气稍正式些，可放在句首，也可放在句中，主句中不能再用 but，但可以用yet;as所表示的语气较强，引导的让步状语从句用倒装语序;however引导让步状语从句时，它的后面可跟形容词或副词，也要用倒装语序。例如：

Although they are poor they are happy. 虽然他们很穷，但很快乐。

Angry as he was, he managed to speak calmly. 虽然他很生气，但是他讲话很平静。

However hard the question is, he can answer it. 不管问题有多难他都能回答。

注意：当as引导让步状语从句时，句子的倒装语序有以下三种形式：

(1). 形容词或副词+as+主语+连系动词be或实义动词。例如：

Rich as he is, he never spends a cent on clothes. 虽然他很富有，但他从不花一分钱在衣服上。

Much as I admire his courage, I don't think he acted wisely. 我虽然佩服他的勇气，但我认为他这样做是不聪明的。

(2). 名词+as+主语+连系动词be (注意句首的名词不带冠词)。例如：

Child as he is, he knows a lot. 尽管他是个孩子，但懂很多事情。

Boy as he was, he was chosen king. 尽管他还是个孩子，但却被立为国王。

(3). 实义动词+as+主语+助动词[如果没有助动词，则要加上一个do(does或did)]。例如：

Try as he may, he never succeeds. 尽管他很努力，但总是不成功。

Change your mind as you will, you will gain no additional support. 即使你改变主意，你也不会得到另外的支持。