how do i know when to use avoir or etre with a verb in the passe compose?

although there are hundreds of verbs in french, knowing when to use avoir or etre is really easy! there are the 13 main verbs that always take etre, and these can be remembered using the acronym MRS VANDERTRAMP (mourir, rester, sortir, venir, aller, naitre, descendre, entrer, rentrer, tomber, retourner, arriver, monter, partir). As well as this, any compound of these verbs also uses etre, so 'repartir' would use etre. Finally, all reflexive verbs use etre in the passe compose. With these rules you will always use the correct auxiliary in the passe compose!