The reason ____I'm writing is to tell you about a party on sunday为什么用for 不用why

问题描述:

The reason ____I'm writing is to tell you about a party on sunday
为什么用for 不用why

the reason for +短语
如:The reason for the change is lack of money.
the reason why + 从句
如:The reason why I beat you is that you do not obey the order.