The verb and its preposition: à, de or none

There is no single reliable semantic rule that separates these three groups. Some verbs take “à”: “commencer à”, “apprendre à”, “réussir à”, “arriver à”, “continuer à”, “hésiter à”. Others take “de”: “essayer de”, “décider de”, “oublier de”, “refuser de”, “finir de”, “arrêter de”. And others take nothing: “vouloir”, “pouvoir”, “devoir”, “aimer”, “préférer”, “espérer”, “aller”, “savoir”.

That third group is the one that trips people up, because it is invisible. “Je veux partir”, “je vais chercher le pain”, “j'espère venir”: there is nothing between the two verbs, and putting something in is as wrong as leaving it out where it belongs.

Learning the preposition separately from the verb does not work, because there is no rule to look up. What works is learning the pair whole: not “decide” and then “de”, but “décider de”, the two words together, as if they were one.

And some verbs change meaning with the preposition rather than changing construction. “Jouer à” is to play a game — “jouer au tennis” — and “jouer de” is to play an instrument — “jouer du piano”. “Penser à” is to have something on your mind; “penser de” is to have an opinion about it.