定语从句是修饰名词或代词的。以下是精品小编为大家整理的高一英语Unit4定语从句知识点，希望对你有帮助!

语法----定语从句知识点

概念：在复合句中，修饰名词或代词的从句叫做定语从句。

成分：先行词，即被定语从句修饰的名词或代词;关系代词：that，which，who(宾格为whom,所有格为whose);或者关系副词where，when，why等。关系代词或关系副词处在先行词和定语从句之间，起着连接主从句的作用。

1. 关系代词that的用法

关系代词that在定语从句中既能指人，也能指物;既能做主语，也能做宾语

例：1)A plane is a machine that can fly. (指物，作主语)

2)The noodles (that) I cooked were delicious. (指物，作宾语)

3)Who is the man that is reading a book over there? (指人，作主语)

4)The girl (that) we saw yesterday was Jim’s sister,(指人，作宾语)

2. 关系代词which的用法

关系代词which在定语从句中只能指物，但既可以做宾语也能作主语

例：1)They planted some trees which didn’t need much water. (作主语)

2)The fish (which) we bought this morning were not fresh. (作宾语)

3. 关系代词who，whom的用法

关系代词who,whom 只能指人，在定语从句中分别作主语和宾语

例：1)The foreigner who helped us yesterday is from USA.(作主语)

2)The person to whom you just talked to is Mr. Li. (作宾语)、

4. 关系代词whose在的用法

关系代词whose为关系代词who的所有格形式，其先行词既可以是人也可以是物，whose和它所修饰的名词在定语从句中既可以做主语也可以做宾语。

例：1)This is the scientist whose name is known all over the world. (指人，作主语)

2) The room whose window faces south is mine. (指物，作主语)

3)He has written a book whose name I’ve forgotten. (指物，作宾语)

5. 关系副词when的用法

关系副词when在定语从句中作时间状语

例：1)I’ll never forget the time when (=during which) we worked on the farm.

2) Do you remember the afternoon when (=on which) we first met three years ago?

6. 关系副词where在定语从句中的用法

关系副词where在定语从句中做地点状语

例：1)This is the place where( =at/ in which) we first met.

2) The hotel where (= in which ) we stayed wasn’t very clean.

7. 关系副词why在定语从句中的用法

关系副词why在定语从句中作原因状语

例: 1). I didn’t get a pay rise, but this wasn’t the reason why(= for which) I left.

2). The reason why (=for which) he has late was that he missed the train.

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