定义 / 说明
限定性定语从句用于明确“到底是哪一个人/事物”。它提供必要信息，因此不加逗号。常见规则是：人用 who，物用 which，而口语里 that 常可用于二者。这个结构能把两句短句合并成一句长句，既清楚又避免重复。
关键规则
- 人用 who：the man who helped me。
- 物用 which：the book which I bought。
- 在很多日常句子中，that 可用于人或物。
- 限定性定语从句不使用逗号。
- 定语从句紧跟在它所修饰的名词后面。
例句
- That is the man who helped me. - 那就是帮过我的那个人。
- This is the book that I like. - 这是我喜欢的那本书。
- The girl who sits there is my sister. - 坐在那里的女孩是我妹妹/姐姐。
- I need a phone that works well. - 我需要一部好用的手机。
- The dog which lives next door is very friendly. - 住在隔壁的那只狗很友好。
常见错误
- ❌ That is the man which helped me. -> ✅ That is the man who helped me.
- ❌ This is the book, that I like. -> ✅ This is the book that I like.
- ❌ I need a phone who works well. -> ✅ I need a phone that works well.