I have noticed that in Polish, the verbs that require the genitive case are those where a preposition is implied or expressed. For example: potrzebować = to need = to have need (of). Szukać = to look (for). Słuchać = to listen (to). Użyć = to use = to have use (of). So it seems to me that the general rule in Polish is to use the genitive case after a preposition or an implied preposition - is that true?