Question

We forgot ... the letter. Sorry, you asked to do it.
a) posting
b) to post
c) post
d) having post
e) posted

I'm looking out of the window, but i am not ... him
a) not see
b) haven't seen
c) don't see
d) am not seeing
e) doesn't see

Answer 1

1) b) to post
2) c) don't see

Answer 2

We forgot to post the letter. Sorry, you asked to do it. (b)
I'm looking out of the window, but I don't see him. (c)