定语从句是英语语法应用英语语法中非常重要的一个部分，它是定语一种修饰句子中某个名词或代词的从句，作用是从句对先行词进行进一步的说明或限制。在实际应用中，英语语法应用定语从句可以帮助我们更准确地表达自己的定语意思，使句子更加清晰明了。从句以下是英语语法应用一些定语从句的应用场景：
形容词性从句是最常见的一种定语从句，它一般用来对先行词进行形容或描述。定语在形容词性从句中，从句关系代词有三种选择：who, which, that。英语语法应用例如：
He is the man who helped me yesterday.
This is the book that I borrowed from the library.
The car which he bought yesterday is very expensive.
副词性从句是定语用来修饰先行词的地点、时间、从句原因、英语语法应用目的定语等概念的从句，一般由关系副词引导，从句如where, when, why。例如：
This is the place where we first met.
Do you remember the day when we went to the beach?
I don't know the reason why he left so suddenly.
有时候定语从句中会含有介词，这时候需要使用介词+which的结构来连接从句，如in which, on which, for which等。例如：
The house in which they live is very old.
The project on which they are working is top secret.
She has a lot of friends, with whom she likes to go shopping.
以上仅是几种常见的定语从句用法，实际上根据具体语境和需要，我们可以灵活运用不同的从句结构来表达自己的意思。定语从句的正确使用不仅可以使句子更加地道和丰富，也能帮助我们在表达中更加准确和清晰。
