1. who/whom/that

　　 三者都可指代人: who作主语, whom 作宾语, that既可以作主语, 又可作宾语。如:

He is a good teacher who/that is loved by all.

　　 Here is the man (whom) you are looking for.

　　 注意: ①在口语中, who 可以代替whom作宾语。②关系代词在定语从句中作宾语时, 一般可省略。

　　 2. whose 可修饰人,也可修饰物; 修饰物时, 可与of which换用,whose在定语从句中作定语。如:

　　 I saw some trees whose leaves were black with diseases.

　　 = I saw some trees the leaves of which were black with diseases.

　　 3. that/which/that/which指代物, 在定语从句中可作主语或宾语。如:

　　 Emei is a wonderful place which/that is worth visiting.

　　 The film (which/that) we saw last night is wonderful.

　　 二、须特别注意以下几种特殊情况:

　　 1. 常用that 不用which的情况:

　　 ① 先行词为all, anything, everything, nothing, something等时。如:

　　 I will do all (that) I can to help you.

　　 ② 先行词被序数词、形容词最高级或the only, the very等所修饰时。如:

　　 He was the only person that joined the army in his village that year.

　　 ③ 先行词既有人,又有物时。如:

　　 They talked about the people and the things (that)they remembered in the school.

　　 ④ 当主句是以who 或which开头的疑问句时, 定语从句用that 引导, 以避免重复。如:

　　 Who is the boy that was here just now?

　　 2. 若被修饰的名词充当从句介词宾语时, 介词可提前于引导词之前,此时的引导词只能用whom 或which。如:

　　 The pencil with which he was writing broke.

　　 3. 当先行词为way时,其后的定语从句用in which或 that引导,也可不用引导词。如:

　　 I don’t like the way (in which/that) he talks to me.