定語從句中會有引導詞，那麼定語從句引導詞有哪一些呢?以及他們的用法又是什麼呢?
1. 關係代詞有：that,which,who,whom,whose,在定語從句中作主語、賓語中表語，whose作定語。代人的有：who,whom,whose,that;代物的'有：that,which,whose.例如：
The man who helped you is Mr White.(who代人，在定語從句中作主語)
That is the person(whom/who/that) you want to see.(whom,who,that代人，在定語從句中作賓語，可省略)
Im not the fool(that) you thought me to be.(that代人，在定從中作表語)
A dictionary is a useful book which(=that) tells us the meaning of words(which或that代物，在定從中作主語)
2. 關係副詞有：when(指時間)，where(指地點),why(指原因)，在定語從句中作狀語。
例如：Would you suggest a time(when) we can have a talk?(when可省略)
The house where they live is not very large./This is the reason why he did not came to the meeting.
注意：不是表時間的先行詞都用when引導定從，不是表地點的先行詞都用where引導定從。例如：Well visit the factory which(=that) makes radios.
(which或that在定從中作主語，where不可用主語，故不可用)
They still remember the happy days(which/that) they spent in Beidaihe.
(which或that在定從中作spent的賓語，when不可作賓語，故不可用)
