一、基本知識精講
被定語從句修飾的名詞或代詞叫先行詞。用來引導定語從句的詞叫關係詞(分為關係代詞和關係副詞)。定語從句一般放在先行詞之後。如： 先行詞 關係詞 定 語 從 句 一、由關係代詞引導的定語從句
英語中的關係代詞有who, whom, whose, which, that 和as。
它們的用法如下：
1. who，whom的.用法
who 和 whom 指人，在從句中分別作主語、賓語。作動詞賓語時常被省掉。在口語中可用who代替whom。 The young worker who invented this tool is her brother.
This is the boy (whom) I helped.
2. which的用法
which指物，在從句中作主語或賓語，作賓語是在非正式語體中可以省略。如：
The factory which produces these cars is very large.
This is the book (which) you want.
3. whose 的用法
whose指人或物，在從句中作定語，不可省略。Whose有時可用of which替換。如：
Do you live in the room whose window opens to the west?
This is the student whose pronunciation is the best in our class.
4. that的用法
that既可指人，也可指物，在從句中作主語或賓語。作賓語時，在非正式語體中常省略。如： There were once six blind men that/ who lived in a village in India.
Wheat is a plant that/ which is grown in the north of China.
用which不用that的情況
1.在引導非限定性定語從句時。 (錯)The tree, that is four hundred years old, is very famous here.
2.先行詞指物，且介詞後
We depend on the land
We depend on the land .
3.先行詞本身是that時
I don’t he did.
二、關係副詞引導的定語從句
英語中的關係副詞有when，where，why等。在定語從句中充當狀語，一般不可省略。
1. when的用法
when指時間、修飾表示時間的先行詞，在定語從句中作時間狀語，相當於at/ in/ on which。如：
How can I forget the day when (=on which) I joined the Youth League?
I thought of the days when (=in which ) we studied together.
He came at a time when the students needed him.
2. where的用法
where指地點，修飾表示地點的先行詞，在定語從句中作地點狀語，相當於in/ on/ at which。如：
This is the farm where (=on which) my grandfather once worked.
That is the place where (=in which) we lived two years ago.
3. why的用法
why指原因，修飾名詞reason，在定語從句中作原因狀語，相當於for which。如：
I don’t know the reason why (=for which) you get so angry with me.
