as作连词的用法

as作连词的用法

As用作连词可以引导时间状语从句、原因状语从句、让步状语从句、方式状语从句、比较状语从句、定语从句和结果、目的状语，我们在学习过程中应注意辨别。

一、时间状语从句

as引导的时间状语从句多用于口语，强调主句和从句的动作同时发生或一前一后发生，意为随着……、一边……一边……有时可以和when和while互换，意为当……的时候。如：

As time went on，her hair became grey．

I read the letter as I walked along the river．

As(when he was) a small boy, he began to learn English

As (While) the teacher is explaining the text，the students are taking notes．

二、原因状语从句

as引导原因状语从句，意为由于……鉴于……语气比because、since弱，表示明显的或已为对方所熟悉的原因，一般放在主句之前。如果放在主句之后，则表示对主句附加说明。如：

As it is raining hard，we won’t go out．

We a11 1ike her as she is kind．

As he was in hurry, he left his bag at home．

三、让步状语从句

as引导让步状语从句，意为虽然，尽管，通常从句要用倒装，即从句的表语／状语放在as之前。如果从句中表语是单数名词，那么名词前不加冠词。如：Young as he is，he knows a lot．（young作表语）

Hard as he works，he has made little progress．（hard作状语）

Child as he is，he knows a lot．（child前不加冠词）

四、方式状语从句

as作方式状语，意为正如、按照、如同、像。如：

I have changed it as you suggested．

You must do everything as I do．

He writes as his teacher does．

五、比较状语从句

as作比较状语，意为像……一样，常用在结构as…as…中，其中前一个as 是副词，后一个as是连词，否定结构为not as／so…as…。如：

This line is as long as that one．

She doesn’t sing as／so well as her sister．

六、结果和目的状语

引导结果和目的状语时，意为“以至于，以便”。如：

Will you be so good as to help us？（表目的）

He raised his voice so as to be heard．（表结果）

七、定语从句

as既可引导限制性定语从句，也可引导非限制性定语从句。在定语从句中，as作主语、表语或宾语时，均不能省略。

1. as引导限制性定语从语时，主要用于the same…as／that、such…as…、as…as…、so…as…等结构，译为“正像，正如”。如：

He is such a lazy man as nobody wants to work with．（宾语）

Don’t trust such people as praise you to your race and speak ill of you behind your back．（主语）

Such girl as she is should be praised．（表语）

As many people as are present have voted for the candidate．（主语）

注意：the same…as与the same…that的区别是：前者表示同类事物中的不同事体，后者表示同一事物。如：

This is the same watch as I lost．（这块表跟我丢失的那块表一样）

This is the same watch that I lost．（这就是我丢失的那块表）

2. as引导非限制性定语从句时，意为正如、正像，先行词通常不能是主句中的某个具体词，而应该是整个语句表达的全部内容或整个短语推断出来的概念。从句可放在主句前、主句后或插入主句中间。其中位于句首时，可构成以下常见结构：as is well known众所周知、as often happens这种情况经常发生、as is often the case情况常常这样、as is supposed如所预料的，as has been pointed out如所指出的、as has been said before如前所说、as is usual（某人通常会）等。如：

He saw the girl，as he hoped he could．

As is often the case，we have worked out the production plan．

He，as we all know, is a good student．

He got married again，as was expected．