Have

Suivi d’un participe passé, l’auxiliaire have sert à former les ‘perfects‘ :Present Perfect -> He has understood. Il a compris.
Past Perfect -> She had done a great job. Elle avait fait un excellent travail.
Future Perfect -> They will have finished by tomorrow. Ils auront fini d’ici demain.
Conditional Perfect -> We would (ou We’d) have won the game if we had had a great player like him. Nous aurions gagné le match si nous avions eu un joueur tel que lui.
Auxiliary + have + past participle -> She must have called. Elle a dû appeler.