Hello. How do I know whether an adjective belongs to the first or the second group? I don't see any patron to determinate it. Dificilis = First group. Humilis = Second group. Asper = First group. Celer = Second group. I can't figure it out. It has nothing to do with the ending syllable. Do I have to learn it by heart? Can I found in a dictionary which group the adjective belongs to? Thanks in advance.