-- the letter on your way to office.--O K. I .A. Don’t forget posting; willB. Do remembe

-- the letter on your way to office.
--O K. I .
A. Don’t forget posting; will
B. Do remember to post; will
C. Do forget to post; do
D. Do remember posting; do

A. Don’t forget posting; will(答案→)B. Do remember to post; willC. Do forget to post; doD. Do remember posting; do解析：forget后接动名词表示忘记做某事，接不定式表示忘了去做某事，还没做；remember后接动名词表示记得做过某事，已做。接不定式表示记住要做某事。对于祈使句的回应，一般用助动词wil。结合语境可知选B。

哦，回答的不错