Hi Vincent. In Brazilian Portuguese we have many ways to speak the past tense... In the case of the ”imperfect past” tense you can add the suffix ”ia” or "ava" after the verb. Already in the "past perfect" tense you can add the suffixes ”ara”, "era" or "ira" after the verb... In the "past perfect" tense, the last letter is usually replaced by "i" or "ei'. But it depends on the verb... In any case, we also have irregular verbs. So the ideal would be for you to inform which verb you have doubts.