1.The man is a worker.
2.The man is speaking at the meeting.
合并句子:
The man who is speaking at the meeting is a worker.
定语从句
概念:在复合句中修饰名词或代词       句子.
(Attributive clause)
Mary is a beautiful girl.
Mary is a girl who has long hair.
形容词作定语
句子作定语,修饰girl, 叫做定语从句