【定语从句中】在英语语法中，定语从句是用于修饰名词或代词的一种从句结构。它通常由关系代词（如 who, whom, whose, which, that）或关系副词（如 when, where, why）引导，起到限定或补充说明主句中先行词的作用。
定语从句的使用不仅使句子更加丰富和具体，还能帮助读者更清晰地理解句子的逻辑关系。掌握定语从句的用法，对于提高英语表达能力和阅读理解能力都具有重要意义。
一、定语从句的基本结构
| 结构类型 | 举例 | 说明 |
| 主语从句 | The book that I bought yesterday is very interesting. | “that I bought yesterday”修饰“book”，作主语部分的定语 |
| 宾语从句 | I don’t know who called me last night. | “who called me last night”作“know”的宾语 |
| 表语从句 | This is the place where we met. | “where we met”作表语，修饰“place” |
| 同位语从句 | The fact that he passed the exam surprised everyone. | “that he passed the exam”解释“fact”的内容 |
二、关系代词与关系副词的用法对比
| 关系词 | 用法 | 举例 |
| who | 指人，在从句中作主语 | The man who is talking to Mary is my teacher. |
| whom | 指人，在从句中作宾语 | The girl whom you saw yesterday is my sister. |
| whose | 表示所属关系 | The student whose essay won the prize is from Class 3. |
| which | 指物，在从句中作主语或宾语 | The car which is parked outside is mine. |
| that | 指人或物，在从句中作主语或宾语 | The book that I read was very interesting. |
| when | 表时间，在从句中作时间状语 | I still remember the day when we first met. |
| where | 表地点，在从句中作地点状语 | This is the house where I grew up. |
| why | 表原因，在从句中作原因状语 | That’s the reason why she left. |
三、定语从句的常见错误与注意事项
1. 误用关系词：
- 错误：The man which is standing there is my father.
- 正确：The man who is standing there is my father.
2. 省略关系词的情况：
- 当关系代词在从句中作宾语时，可以省略。
- 正确：I saw the movie (that) I liked.
- 错误：I saw the movie which I liked.（虽然语法上不完全错误，但口语中更常省略）
3. 避免重复使用“that”：
- 在非限制性定语从句中，不能使用“that”。
- 正确：My brother, who lives in Beijing, is a doctor.
4. 注意从句中的动词时态：
- 从句中的动词时态应与主句一致。
- 正确：She told me that she had already left.
四、总结
定语从句是英语中非常重要的语法结构，能够有效增强句子的表现力和准确性。通过合理使用关系代词和关系副词，可以让句子更加清晰、自然。在实际应用中，需要注意关系词的选择、从句的位置以及是否省略等问题。熟练掌握定语从句，有助于提升英语写作和口语表达能力。