定语从句是英语语法中的一个重要概念，它用来修饰名词或代词，通常由关系代词或关系副词引导。下面是一些定语从句的例子：
1. The book that I borrowed from the library is very interesting. （关系代词 "that" 引导的定语从句）
2. The man who you met just now is my friend. （关系代词 "who" 引导的定语从句）
3. I have a sister who is a doctor. （关系代词 "who" 引导的限定性定语从句）
4. The glass that was broken by my brother is very expensive. （关系代词 "that" 引导的定语从句，过去分词作定语）
5. The place where I was born is where I want to visit next. （关系副词 "where" 引导的定语从句）
6. The reason why he is absent today is that he is sick. （关系副词 "why" 引导的定语从句）
7. The students who take physical exercise live longer. （关系代词 "who" 引导的限定性定语从句）
8. The United States is known for its supermarkets, where huge quantities of all kinds of food and household articles are sold. （关系副词 "where" 引导的定语从句）
9. The boy who is playing football is my brother. （关系代词 "who" 引导的定语从句）
10. The time when we met for the first time was unforgettable. （关系副词 "when" 引导的定语从句）
这些例句展示了定语从句在英语中的不同用法，包括限定性定语从句和非限定性定语从句，以及关系代词和关系副词的不同用法。希望这些例子能帮助你更好地理解定语从句
