一关系代词的用法
1 who→在定语从句中做主语→用来指人
例句：我喜欢那个来自美国的男孩儿.
I like the boy who is∕comes from America.
2 whom在定语从句中做宾语→用来指人
例句：①我喜欢的那个男孩儿是汤姆.
The boy whom I like is Tom.
②你正在等的那个医生现在在房间里.
The doctor whom you are waiting for is in the room now.
3 whose在定语从句中做定语→用来指人或指物
例句：①我认识那个叫汤姆的男孩儿.
I know the boy whose name is Tom.
②他喜欢那个窗户朝南开的房间.
He likes the room whose windows open to the south.
4 which→在定语从句中做主语或宾语→用来指物
例句：①这是你想要的那本书.
This is the book which you want.
②我喜欢红色的那辆车.
I like the car which is red.
5 that→在定语从句中做主语或宾语→用来指人或指物（可以用who, whom, which替换）
※ 必须用that的7种情况：
⑴先行词是all, everything, nothing, few, little等不定代词时,必须用that引导.
例句：我会告诉你我知道的一切.
I shall tell you everything that I know.
⑵当先行词被序数词或形容词最高级修饰时必须用that引导.
例句：①我不会忘记我学过的第一课.
I can’t∕won’t forget the first lesson that I learned.
②他是我见过的最可恨的人.
He is the most hateful person that I’ve seen.
⑶当先行词被all, every, little, few, no等修饰时,必须用that引导.
例句：我喜欢你给我的所有的书.
I like all the books that you gave me.
⑷当先行词被the only（唯一的）；the very（恰好,正好）；the same（相同的）；the last(最后的)等修饰时,必须用that引导.
例句：你是我唯一喜欢的人.
You’re the only person that I like.
⑸当先行词既有人又有物时,必须用that引导.
例句：我不知道他们正在谈论的人和事.
I don’t know those persons and things that they are talking about.
⑹当that用做关系副词,修饰表示时间的名词时,可以代替when来引导.
例句：我不会忘记我第一次见到你的那一天.
I can’t forget the day that∕when I first met you.
⑺当句子中已有who出现时,必须用that引导.
例句：正在唱歌的那个女孩是谁?
Who is the girl what is singing?
6 as→在定语从句中做主语或宾语→用来指人或指物.
such…as… 如此像…,这样的像…,像…一样
the same…as… 相同的…,像…一样
例句：你们正在唱的那样的歌很流行.
Such songs as you’re singing are popular now.
二关系副词的用法
1 when→先行词表示时间
例句：我不能忘记在上海的那些日子.
I can’t forget those days when I was in Shanghai.
2 where→先行词表示地点
比较：where→定语从句中谓语动词为不及物动词时用.
that∕which→定语从句中谓语动词为及物动词时用.
例句：This is the place where I lived(不及物动词) last year.
This is the place which∕that(及物动词) last year.
3 why→先行词只有一个reason（原因）
例句：这就是我喜欢你的原因.
This is the reason why I like you.
