在英语语法中，定语从句用于修饰名词或代词，可以使用when、where和why等引导词来表示时间、地点和原因。例如，"The day when we met was a sunny day."，"The place where we met was a coffee shop."和"The reason why she was late is that she missed the bus."等。掌握定语从句的用法对于提高英语语言能力至关重要。
时间状语从句
当我们需要描述一个时间点或时间段时，可以使用定语从句来修饰名词或代词。此时，我们可以使用when来引导时间状语从句。例如：
- The day when we met was a sunny day.
- The time when she arrived was late at night.
地点状语从句
当我们需要描述一个地点或场所时，同样可以使用定语从句来修饰名词或代词。此时，我们可以使用where来引导地点状语从句。例如：
- The place where we met was a coffee shop.
- The city where she grew up is very beautiful.
原因状语从句
当我们需要描述某个事件或情况的原因时，我们可以使用定语从句来修饰名词或代词。此时，我们可以使用why来引导原因状语从句。例如：
- The reason why she was late is that she missed the bus.
- The reason why he chose this university is that it has a good reputation.
