Question

Como e quando devo usar o was, were e weren't no ingles?

Answer 1

O was/were é o verbo to be no passado
o was é usado no I (eu) he (ele) she (ela) it (para objetos e animais)
o were é usado no you (você) we (nós) they (eles)
o weren't é o were na negativa

Answer 2

Passado verbo to be

Afirmativa - was ( I ,he,she ,it)
Negativa   - wasn't (I,he,she,it)

Afirmativa - were (you,we,they)
Negativa  -  weren't (you,we,they)