一、关系代词引导的定语从句

who（作主语）

The students who passed the exam are going on a trip next week. （通过考试的学生下周要去旅行。）

whom（作宾语，可省略）

The book which/who I borrowed from the library is very interesting. （我从图书馆借的那本书很有趣。）

whose（作定语）

The girl whose cat is missing is very worried. （猫失踪的女孩非常担心。）

that（作主语/宾语）

The movie that started at 7 PM was fantastic. （晚上7点开始的那部电影太棒了。）

which（作主语/宾语）

The car which is parked outside belongs to my neighbor. （停在外面的车属于我的邻居。）

二、关系副词引导的定语从句

when（作时间状语）

The song which was sung at the concert is my favorite. （音乐会上唱的那首歌是我最喜欢的。）

where（作地点状语）

The house where we grew up has been renovated. （我们长大的房子已经翻新了。）

why（作原因状语）

The reason why he was late is that he forgot his wallet. （他迟到的原因是忘记带钱包了。）

三、特殊用法例句

省略关系代词

The man I met yesterday is my friend. （我昨天遇到的那个人是我的朋友。）

非限制性定语从句前置

The book, which I read last month, was very inspiring. （我上个月读的那本书非常有启发性。）

限定性定语从句

The only student who passed the exam is Zhang Wei. （唯一通过考试的学生是张伟。）

幽默用法

The man who is shaking hands with my father is a policeman. （和我的父亲握手的男人是警察。）

四、长句拆分示例

原句：The professor whom you are waiting for has just finished his lecture.

拆分后：The professor [who you are waiting for] [has just finished] his lecture. （你等待的教授刚刚结束了讲座。）

注：关系代词who和whom在口语中常可互换使用，但whom仅用于作宾语。建议结合具体语境选择合适的关系词，并注意先行词的限定条件。