定语从句的组成？

定语从句概要：
（这是有关定语从句的精要介绍，涵盖了有关定语从句的各个方面，供参考：）

引导定语从句的关联词包括关系代词和关系副词。关系代词有that, which, whose, who, whom, as；关系副词有when, where, why。关系代词和关系副词在定语从句中都充当一定的句法成份。关系代词在从句中充当动词的宾语时一般可以省略。
关系代词的选用比较复杂，受下列条件的制约：
(1) 要看先行词是指人还是指物，
(2) 要看关系代词在从句中句法功能，
(3) 要看定语从句是限定性的还是非限定性的。

在定语从句中充当的成分
↓ 用于限定性或非限定性从句 只用于限定性从句
指人 指物 指人或指物
主语 who which that
宾语 whom which that
谓语 whose whose (of which)
That 只能用在限定性定语从句中，而who, whom, which, which 既可用于限定性定语从句中，也可用于非限定性定语从句。
I know that he is a man who means what he says.
I know that he is a man that means what he says. 【我知道他是一个守信用的人。】

The gentleman whom she met addressed her with courtesy.
The gentleman that she met addressed her with courtesy. 【她遇到的那位先生很有礼貌地向她打了招呼。】
The gentleman she met addressed her with courtesy.（在从句中充当动词宾语的关系代词，可以省略。）

The watch which was lost has been found.
The watch that was lost has been found. 【丢了的表找到了