在定语从句中，in which充当一个关系代词，用来连接先行词（指代被修饰名词）和从句。它充当以下语法成分：

定语从句中in which的语法功能

1. 主语

The book in which I found the answer is on my desk. （我找到答案的那本书在我的书桌上。） The students in which the teacher believes are doing well. （老师认为的那些学生表现很好。）

2. 宾语

I don't know the reason in which he left. （我不知道他离开的原因。） The company in which he works is very successful. （他工作的公司非常成功。）

3. 表语

The house in which he was born is still standing. （他出生的房子仍然屹立不倒。） The problem in which we are facing is complex. （我们面临的问题很复杂。）

4. 定语

The house in which I grew up is a special place. （我长大的房子是一个特别的地方。） The book in which I found the recipe is a valuable resource. （我找到食谱的那本书是一份珍贵的资源。）

值得注意的是，in which从句通常修饰先行词而不是整个句子。例如：

The house in which I grew up is old. （我长大的房子很旧。） The book in which I found the recipe was written by my grandmother. （我找到食谱的那本书是我祖母写的。）

与其他关系代词的比较

in which与其他关系代词有相似之处，它们都用来连接先行词和从句。然而，in which更具体地指时间、地点或情况。以下是一些其他关系代词：

who：指代人 which：指代事物 that：指代人或事物

例如：

The man who lives next door is a doctor. （住在隔壁的男子是一位医生。） The car which is parked in the driveway is mine. （停在车道上的车是我的。） The fact that he is lying is obvious. （他撒谎的事实是显而易见的。）