- 分类
(1) 限制性关系分句，无逗号，在句子中的部分不可缺少：
先行词为表示类别的不定冠词 she's a woman who ...
先行词为特指的定冠词 She's the woman who ...
先行词为不定限定词(all, any, some, every, no) Any one who ...
(2) 非限制性关系分句，前面有逗号：
who, whom, whose, which作引导词 The chairman, who gave a speech, was 45.
where, when等作引导词 ... , when ...
各种状语从句
- 关系代词（引导词）
(1)限制性分句中：
分句作主语成分时，who指人，that\which指物
分句作定语成分时，who\whom指人，that指物
分句作介词补足语时，介词前置，for whom, in which ...
分句作主语补足语、there句型时，that可省略
先行词前带有only, all, any 时用that
(2)非限制性分句：
who\whose指人 which\that指物
(3)介词 关系代词：
限定形式 by which, of whom, by the means of which ...
非限定形式 in which to, on which to ...
- 双重关系分句
同层次 A woman whose clothes are good-looking, and whose face is pretty.
不同层次 A boy I know who can swim.
- 嵌入式关系分句
A child who she had talked about was an orphan.
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