Answer:
il y a des professeurs de littérature?
there are literature teachers?
oui, il y a dix-huit professeurs de littérature.
yes, there are eighteen literature teachers.
Answer:
je n'ai pas acheté de chocolat
HEY THERE.
THE ANSWER IS
Imparfait = what was happening all around you (including you), background. Also ongoing events, habits, what used to be.
Passé composé = what took place at that very moment: a specific event or a succession of specific events, the main storyline.