I'm writing to you to tell you what I did in May day.这句子有错吗?

I'm writing to you to tell you what I did in May day.这句子有错吗?
I'm writing to you to tell you what I did in May day.这句子有错吗?

I'm writing to you to tell you what I did in May day.这句子有错吗?
有个介词的小错误.说I'm writing to tell you what I have done on May day.会更贴切一些,当然了,用what I did也是完全可以的

in改成on

I'm writing totell you what I did in May day

in May Day----on May Day 在某一天要用介词on