please remember _____ the letter for me .I forget _______ it his morning.

问题描述:

please remember _____ the letter for me .I forget _______ it his morning.
A.to post,to post B.to post ,posting
选哪个?为什么?

A
remember to do 表示还没做,记得要去做
remember doing 表示已经做了,记得曾经做过