Sur-aller is a french third group verb. So, this verb is irregular and do not follow a regular conjugation pattern like first or second group verbs. Follow this link to see all the endings of the conjugation of most of the third group verbs :
conjugation rules and endings for the second group verbs.
It is possible that
aller is the single most irregular French verb. Its conjugation involve no less than three distinct stems from synonymous Latin roots:
all-/aill-, v-, ir-. Aside from this, most endings are those of first conjugation (
-er) verbs.
Sur-aller 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 »:
« sur-va-t-il ">« aura-t-il sur-allé ? ».
Finally, the interrogative form does not exist in subjunctive and imperative.