定语从句是英语中一种常见的语法结构，它用于修饰名词或代词，提供额外的信息。在定语从句中，被修饰的名词或代词称为先行词，而关系词（如who, whom, whose, that, which等）则引导从句，并在从句中充当一定的成分。

The book which I like the most.

The box which is full of books should be empty as soon as possible.

The whole city, 75% of whose factories and buildings were gone, lay in ruins.

The man who is standing over there is my teacher.

I like the book that you recommended.

The girl whose hair is long is my classmate.

Do you know the boy whose father is a doctor？

The boys who are playing football are from Class One.

Mr. Liu is the person （whom） you talked with on the bus.

The teacher who teaches us math is a young man.

在分析这些例句时，可以看到定语从句的关键组成部分包括先行词、关系词和从句中的谓语动词。关系词在从句中充当主语、宾语或定语，其形式（who, whom, whose, that, which等）取决于先行词的人称和数。

希望这些例句能帮助你更好地理解和运用定语从句。