在定語從句的非限制性定語中,which 和as 是容易混淆的。在很多情況下兩者兼可互換,但在下列情況中不可互換:
(1)通常as 可以放在整句的句首,而which 只能在逗號之後,as 本身含有“正如”,as 在定語從句中既可是主語也可做賓語。
As appear from her paper, she has read widely in Romantic literature.
She is remarkable, as I have told you .
(2)which 在做非限制性定語從句關聯詞時可以無明確先行詞,指前句整個的意思,如:She has married again, which surprises us.
(1)when指時間,其先行詞表示時間,在句中作時間狀語。例如:
This was the time when he arrived. 這是他到達的時間。
(2)where指地點,其先行詞表示地點,在句中作地點狀語。例如:
This is place where he works. 這是他工作的地點。
(3)why 指原因,其先行詞是原因,起原因狀語作用。例如:
Nobody knows the reason why he is often late for school. 沒人知道他為什麼上學總遲到。
在定語從句中,許多人往往分不清all that 和what,what 實際上只引導名詞性從句,它相當於all that 兩個字,例如:
All that I know is that he has made up his mind to heave the country for a new place.
= What I know is that he has...
在複合句中,修飾某一名詞或代詞的從句叫定語從句。被修飾的名詞或代詞叫先行詞,定語從句一般放在先行詞的後面。