who can explain this sentence for me ?

来源:百度知道 编辑:UC知道 时间:2024/05/15 10:46:20
I am writing in reply to a letter I received from you a few days ago.
here i have some puzzles. what does the "in" mean? what role does it play ?

本信是回复几天前收到的你的那封信。

in reply to 是个词组,答复的意思

有一个词组是in reply to sth.作为回复
in是个介词 in reply to sth.在句子中作状语

我写这封信是为了回复你几天前写给我的信.
我有一些疑问。“in”是什么意思,在这里,它扮演什么角色?