Maintenir belong to the 3
rd group. Maintenir is a common french verb.
Maintenir is conjugated the same way that verbs that end in :
-enir
Maintenir is conjugated with
auxiliary avoir.
Maintenir verb is
direct transitive.
French verb maintenir can be conjugated in the reflexive form:
Se maintenir
Maintenir verb is a direct transitive verb, so passive voice can be used.