An auxiliary verb, or helper verb, is a conjugated verb that comes before a main verb and determines the main verb's tense, mood, or aspect (e.g. I have gone.).
I ought to do itdebería hacerlo;debiera hacerlo;one ought not to do itno se debiera hacer;I ought to have done itdebiera haberlo hecho;you ought to have warned meme deberías haber avisado;he ought to have knowndebía saberlo;I thought I ought to tell youme creí en el deber de decírselo;to behave as one oughtcomportarse como se debe
2(vague desirability)
you ought to go and see itvale la pena ir a verlo;you ought to have seen him!¡tenías que haberle visto!
3(probability)deber
he ought to windebería ganar;that ought to be enoughcon eso debería ser suficiente;he ought to have arrived by nowdebería de haber llegado ya