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(dāng)……的時候",引導(dǎo)時間狀語從句。注意與when、 while的用法區(qū)別。
① when作"當(dāng)……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(jìn)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(dǎo)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(dǎo)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(dǎo)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(dǎo)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(dǎo)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(dāng)先行詞被the same, such等詞修飾時,常用as來引導(dǎo)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(dǎo)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)
