why are we using "de" after oublie?
certain verbs use certain prepositions to introduce infinitives or nouns. oublier uses de. here is a list for de and here is one for à
J'ai oublié de laisser un pourboire pour le serveur.
Not today! I put that but it corrected it to au serveur
check for another error. it is listed as accepted.
and not in May 2021 either... quel dommage
In the real world you can use either as suits the situation, but if Duo says "laisser", then it means "to leave".
Why au and not pour le serveur