我們知道,as和which作爲關係代詞都可以用來引導非限制性定語從句,指代整個主句所表達的內容,在從句中作主語或賓語,但它們在用法上有區別,這一點許多學生往往搞不清楚。現就它們引導非限制性定語從句的用法簡述如下:
一、相同之處
當從句位於主句之後,引導詞指代整個主句所表達的全部意義時,as和which可以互換。如:
The elephant is like a snake,as/which everybody can see.
大家都看得出,這頭大象像條蛇。
A big earthquake occurred there last night,as/which was reported on TV.
據電視報道,昨夜那裏發生了大地震。
She is from Shanghai,as/which I know from her accent.
她來自上海,那是我從她的口音知道的。
二、不同之處
1、as引導非限制性定語從句時,位置比較靈活,可位於主句之前,也可位於主句之中或之後;而which引導非限制定語從句只能位於主句之後,不能位於主句之前。如:
_______ is known to everybody,the moon travels round the earth.
h
答案:B
_______ is mentioned above,the number of the students in senior high schools is increasing.
h
答案:B
Air,as we know,is a gas.衆所周知,空氣是一種氣體。
He is very careful,as his work shows.
他的工作表現表明他非常謹慎。
as引導非限制性定語從句常有“如同......那樣”的含義,因此在一些固定結構中,如:
as we know;as is known to all(衆所周知)
as we all can see(正如我們大家都能看到的那樣)
as has been said before/above(正如前面所述)
as has been pointed out(正如所指出的那樣)
as might be imagined(可以想象得到)
as might be expected(正如所預料的那樣)
as is often the case(情況通常是這樣)
以上種種固定搭配,一般不能用which代替as。
2、搭配上,在由the same或such所修飾的名詞後通常用as作關係代詞引出非限制性定語從句。如:
I have got into the same trouble as he (has).
我遇到了與他一樣的麻煩。
I've never heard of such a moving story as he is telling.
我從未聽過像他講得那麼有趣的故事。
3、which引導的從句在意義上相當於一個並列句,可以用and this代替,意思是“這件事”;as引導的從句主要起連接上下文的作用,表達說話人的觀點、看法,並指出主句內容的根據或出處等。如:
He sold his new car,which surprised me.
=He sold his new car,and this serprised me.
Einstein,as we know,is a famous scientist.
我們都知道,愛因斯坦是一位著名的科學家。
As is known to all,Taiwan is part of China.
衆所周知,臺灣是中國的一部分。
4、當which在從句中指代的是先行詞本身而不是主句時,不可用as代替which。如:
The peach tree,which I planted last year,has not borne any fruit.
這棵桃樹是我去年種下的.,還沒有結出任何果實。
The book,which I bought yesterday,is very instructive.
我昨天買的這本書很有教育意義。
5、在從句中作主語時,which既可作系動詞be的主語,也可作實義動詞的主語,而as只可作系動詞be的主語。如:
He married her,which was nature.(可用as代替which)
他和她結婚了,這是很自然的事。
She met the boy,which delighted her.(不可用as代替which)
她見到了那個男孩,這使得她很高興。
He failed in the exam again,which made his parents very angry.
他考試有不及格了,這是他父母很生氣。
6、as引導的從句在意義上不可與主語相悖,而which引導的從句則不受此限制。
Mum treats me like a baby,which I can't bear.
媽媽把我當小孩看待,這是我不能忍受的。