as可以作連詞、介詞及關(guān)系代詞.現(xiàn)將其用法小結(jié)如下:
一、 as作連詞的用法:
1.作"當……的時候",引導時間狀語從句.注意與when、 while的用法區(qū)別.
① when作"當……的時候"解,可以指較短的(一點)時間,也可指一段時間.如:
When he was at college,he could speak several foreign languages.
When the clock struck twelve,all the lights in the street went out.
② while常表示一段較長的時間或一個過程,強調(diào)主句謂語動詞與從句謂語動詞同時發(fā)生.如:
Work while you work.Play while you play.
③ 但屬下列情形時,只用as,而不用when或while.
A) 用于表示同一個人的兩種動作交替進行,指"一邊……,一邊……".如:
The girl dances as she sings on the stage.
He looked behind from time to time as he went forward.
B)表示兩個同步發(fā)展的動作或行為,譯為"隨著……".如:
As time went on / by,she became more and more worried.
As children get older,they become more and more interested in the things around them.
C)表示兩個短促行為或事件幾乎同時發(fā)生.如:
I thought of it just as you opened your mouth.
Just as the flying worm hit her face,she gave a loud cry.
D) 后接名詞表示某一年齡段時,用as.如:
As a young man,he was active in sports.
2.as=since,作"既然"、"由于"解,引導原因狀語從句,常用來表示已為人們所知或顯而易見的原因或理由.如:
As / Since you're not feeling well,you may stay at home.
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,引導方式狀語從句.如:
He speaks English as Americans do.
Remember,you must do everything as I do.
4.用于as...as...或not so/ as...as...中,前一個as是副詞,后一個as是連詞,引導比較狀語從句.如:
They helped the old man as often as possible.
I don't speak English so/ as well as he does.
5.作"雖然"、"盡管"解,引導讓步狀語從句.常用倒裝語序,即adj./adv./ n.+ as +主語+謂語+主句.如:
Tired as they were,they walked on.
Child as he is,he knows a lot.(child前不用冠詞)
二、 as作關(guān)系代詞,引導定語從句,作"正如"、"這一點"解.如:
He is very careful,as his work shows.
As is well-known,Taiwan belongs to China.
as的這種用法,請看2001年的高考題:
is known to everybody,the moon travels round the earth once every month.
A.It B.As C.That D.What
字母下劃橫線的為正確答案)
另外,當先行詞被the same,such等詞修飾時,常用as來引導定語從句.如:
Such a clever boy as he can learn anything quickly.
I was reading the same book as he bought yesterday.
三、 as作介詞的用法:
as引導的介詞短語大多用作狀語,as譯為"作為";少數(shù)情況可引起賓語補足語.如:
As a League member,I'll take the lead in everything.(狀語)
She works as a doctor.(狀語)
They have me as one of their own children.(引起賓語補足語)