1. The perfect construction consists of a conjugated form of the verb /abér/ plus the /-do/ form of the verb.
2. /-do/ forms in perfect constructions are uninflected (do not change their endings); in other constructions, functioning as modifiers, the /-do/ forms do inflect (change their endings) for number and gender.
2. A variant /áy/ occurs as a distinct form not participating in the present perfect construction.
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