In this exercise we have to complete the space with 4 potential correct answers:
As I am at the dentist. I obviously ____ sign for the package.
a) cannot b) can not c) could not d) did
I have chosen "can not" because of the present conjugation in this sentence. Because your English is better than mine, you might choose "cannot" and that's the reason I want to ask you this question. Why and how?