Just four verbs break the imperfect pattern — and they're among the most useful verbs in the language:

Pronoun	Ser	Ter	Vir (to come)	Pôr (to put)
eu	era	tinha	vinha	punha
você / ele / ela	era	tinha	vinha	punha
nós	éramos	tínhamos	vínhamos	púnhamos
vocês / eles / elas	eram	tinham	vinham	punham

• The usual habits hold: eu and ele / ela share a form, and nós carries an accent.
• Pôr is to put — pôr a mesa, to set the table. In everyday speech, many Brazilians say botar instead — and botava is perfectly regular.
• Ir only looks odd: ia, ia, íamos, iam is just the regular -ia ending. Eu ia à praia todo dia. — I used to go to the beach every day.