定语从句

定语从句就是「用一个句子去修饰一个名词」，是 B1 最重要的句式之一——它能让你的句子从简单变复杂。

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基本原理

The man is my uncle. He lives next door.
→ The man who lives next door is my uncle.

被修饰的名词（the man）叫先行词，who lives next door 就是定语从句。

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五个关系词

关系词	先行词	在从句中作	例
who	人	主语／宾语	The girl who sits next to me is Amy.
whom	人	宾语（较正式）	The man whom I met...
which	物	主语／宾语	The book which is on the desk...
that	人或物	主语／宾语	The film that we saw...
whose	人或物	所有格	The boy whose father is a doctor...
where	地点	状语	The town where I grew up...
when	时间	状语	The day when we met...

记住三条就够用：

• 人 → who
• 物 → which
• 人和物都行 → that

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关系词能不能省略？

关键判断：关系词在从句里作宾语时可以省略，作主语时不能。

• The book (which) I bought yesterday is good.✓ 可省（which 是 bought 的宾语）
• The book which is on the desk is mine.✗ 不可省（which 是主语）

判断办法：去掉关系词后，从句里还有没有主语？

• I bought yesterday —— 有主语 I → 可以省
• is on the desk —— 没主语 → 不能省

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限制性 vs 非限制性（带不带逗号）

	限制性（无逗号）	非限制性（有逗号）
作用	不可缺少，去掉句子意思变了	补充说明，去掉不影响
例	The students who failed must retake it.（只有不及格的要重考）	My brother, who lives in Beijing, is a doctor.（我只有一个哥哥）
能用 that 吗	可以	不可以
能省略吗	作宾语时可以	不可以

非限制性从句的两条禁令要记牢：不能用 that、不能省略。 PET 阅读 Part 6 常考。

which 还能指代前面一整件事（只用于非限制性）：

He passed the exam, which made his parents very happy.
（which = 他通过考试这件事）

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介词的位置

The house which he lives in is old.（口语常用，介词在后）
The house in which he lives is old.（正式，介词提前）

注意：介词提前时，只能用 which / whom，不能用 that。

• the house in that he lives（错）

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四个高频错误

1. 多加一个代词：The man who he lives next door...（错，who 已经是主语了）
2. 非限制性用 that：My father, that is a teacher...（错，要用 who）
3. 人物混用：The book who I read（错，要用 which/that）
4. whose 和 who's 混：whose 是「谁的」，who's = who is

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在写作里怎么用

定语从句是把两个短句合并成一个长句的最好工具：

❌ I have a friend. She lives in Shanghai. She is a doctor.
✅ I have a friend who lives in Shanghai and works as a doctor.

每篇作文用 1–2 个定语从句，Language 分立刻不一样。

练习：用关系词合并

1. The girl is my sister. She is wearing a red dress.
2. This is the book. I told you about it.
3. I know a boy. His father works in a hospital.
4. We visited the village. My grandmother was born there.