I can't find a lesson that explains why, for instance, there is no need for a preposition following the conjugated verb espérer in a sentence such as: "J'espère ne pas faire d'erreurs," whereas a sentence such as "il m'a appris à ne pas avoir faire" requires the "à" after the conjugated verb apprendre, just as "le professeur dit de ne pas parler" requries the "de" after dire.
I feel stuck with this problem and would appreciate someone's help.
Thanks so much! Kalpana