Dear MR/MRS XX,
I want to apologize for not replying you for such a long time.Thank you for your suggestions on improving the etiquette of my letter,I will pay more attention to it afterwards.
Yours sincerly,
xxxx
哪位大神来帮我写一封英语信?（本人不太擅长英语,）
Dear MR/MRS XX,
I want to apologize for not replying you for such a long time.Thank you for your suggestions on improving the etiquette of my letter,I will pay more attention to it afterwards.
Yours sincerly,
xxxx