【初中定语从句讲解及练1(7页)】在初中英语学习中，定语从句是一个非常重要的语法知识点。它不仅在阅读理解中频繁出现，也是写作和口语表达中提升语言层次的重要工具。掌握好定语从句，有助于我们更准确地表达复杂的意思，提高英语综合运用能力。
一、什么是定语从句？
定语从句是用来修饰名词或代词的句子，通常由关系代词或关系副词引导。在句子中，它起到“定语”的作用，用来说明先行词的性质、特征或身份。
例如：
- The book that I bought yesterday is very interesting.
（我昨天买的那本书很有趣。）
这里的 “that I bought yesterday” 就是定语从句，修饰先行词 “the book”。
二、定语从句的结构
一个完整的定语从句通常包括以下三部分：
1. 先行词：被修饰的名词或代词。
2. 关系词：引导从句的词，如 who, whom, that, which, whose, when, where, why 等。
3. 从句：由关系词引导的完整句子，对先行词进行补充说明。
三、常用的关系词及其用法
| 关系词 | 用法说明 | 举例 |
|--------|----------|------|
| who| 指人，作主语或宾语 | The girl who is talking to Tom is my sister. |
| whom | 指人，作宾语（口语中常省略） | The man whom you met is a teacher. |
| that | 指人或物，作主语或宾语 | The man that is standing there is my father. |
| which| 指物，作主语或宾语 | The car which is red is mine. |
| whose| 表示所属关系，指人或物 | The student whose bag was stolen is in the office. |
| when | 指时间，作状语 | I still remember the day when we met for the first time. |
| where| 指地点，作状语 | This is the house where I was born. |
| why| 指原因，作状语 | That’s the reason why he left early. |
四、定语从句的注意事项
1. 关系词不能省略：当关系词在从句中作主语时，不能省略。
- 正确：The boy who is playing football is my brother.
- 错误：The boy is playing football is my brother.
2. 当先行词是 all, everything, something, nothing 等不定代词时，通常用 that 引导从句。
- 例如：Everything that he said was true.
3. 当先行词是人和物混杂时，一般用 that 引导从句。
- 例如：The people and things that I saw were unforgettable.
4. 当关系词作宾语时，可以省略。
- 例如：The book (that) I borrowed is on the table.
五、定语从句的练习题（附答案）
第1题
The girl ___ is sitting next to me is my classmate.
A. who
B. which
C. that
D. whom
答案：A
第2题
The book ___ I bought last week is very expensive.
A. who
B. which
C. that
D. whom
答案：B 或 C
第3题
This is the house ___ my grandfather was born.
A. where
B. when
C. which
D. that
答案：A
第4题
The man ___ you met yesterday is a famous doctor.
A. who
B. which
C. that
D. whom
答案：A 或 D
第5题
I don’t know the reason ___ he left so early.
A. why
B. when
C. which
D. that
答案：A
六、总结
定语从句是初中英语学习中的重点内容，掌握好它的基本结构和常见关系词的使用，能够帮助我们在实际交流和写作中更加自如地表达自己的想法。通过多做练习题，结合语境理解，才能真正掌握这一语法点。
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