Auxiliary Verb

Definition: An auxiliary verb is a conjugated verb used in front of another verb in compound tenses in order to indicate the mood and tense of the verb.

In French, the auxiliary verb is either avoir or tre. All French verbs are classified by which auxiliary verb they take, and they use the same auxiliary verb in all compound tenses. Most French verbs use avoir. The following is a list of verbs (and their derivatives) that require tre.

  1. tre (to be)
  2. avoir (to have)
Examples in French:
aller - to go
arriver - to arrive
descendre (redescendre) - to descend / go downstairs
entrer (rentrer) - to enter
monter (remonter) - to climb
mourir - to die
natre (renatre) - to be born
partir (repartir) - to leave
passer - to pass, spend time
rester - to stay
retourner - to return
sortir (ressortir) - to go out
tomber (retomber) - to fall
venir (devenir, parvenir, revenir) - to come
These are all verbs of a certain kind of movement.

You do get used to these verbs over time and one day you'll just know whether to use tre or avoir without even having to think about it.

Some advices for tre and avoir's use:

  1. All pronominal verbs use tre as the auxiliary verb as well:

    se baigner - to bathe
    s'habiller - to get dressed
    s'imaginer - to imagine
    se laver - to wash
    se lever - to get up
    se moquer - to make fun of
    se prparer - to prepare oneself
    se promener - to go for a walk
    se raser - to shave
    se reposer - to rest
    etc.

  2. For all verbs conjugated with tre in all of the compound tenses, the past participle has to agree with the subject in gender and number.

    Il est all - Elle est alle - Ils sont alls - Elles sont alles

  3. Verbs are conjugated with tre only when they are intransitive. When the above verbs are used transitively, avoir is used as the auxiliary verb.

    Je suis sorti
    I went out.

    J'ai sorti la voiture
    I took the car out.

    Il est descendu
    He went downstairs.

    Il a descendu la valise
    He took the suitcase down.



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