Costumer is a french first group verb. So it follow the regular conjugation pattern of the first group like:
aimer.
Follow this link to see all the endings of the conjugation of the first group verbs :
conjugation rules and endings for the first group verbs.
Costumer is conjugated the same way that verbs that end in :
-er.
First group verbs always end with
-er as their infinitive. Endings of first group verbs are regular.
Note : Although endings are perfectly regular, spelling changes occur in the stems of verbs in
-cer,
-ger,
-yer,
-eter,
-eler,
-é-consonne(s)-er,
-e-consonne-er, verb
envoyer and similar verbs.
Costumer verb is conjugated in female form and in reflexive form. Be careful, the past participle of compound tenses must agree with the subject.
Costumer verb is conjugated in interrogative form. For sound reasons, an euphonious
« t » is added to the pronoun of the third person:
« il »,
« elle »,
« on »,
« ils »,
« elles » except when the verb ends with
« t » or
« d »:
« costume-t-elle ? »,
« costuma-t-elle ? »,
« costumera-t-elle ? »,
« a-t-elle costumé ? »,
« aura-t-elle costumé ? ».
Always in interrogative form, and always for sound reasons, an accent appears in first person present indicative tense when the verb ends with
« e ». An euphonious
« e » is replaced by
« é »:
« costumé-je ? ».
Finally, the interrogative form does not exist in subjunctive and imperative.
