Beside three verbs all the verbs in imperfeito are regular. The endings of the verbs in infinitive, -ar, -ir, -er are left out and to what remains, the stem, we ad ava, -avas, -ava, -ávamos, avam to verbs ending in ar and und -ia, -ias, -ia, -iamos, -iam to the verbs ending in -ir and -er.
Concerning the use English native speakers should be aware that the English past tense, I went, can be used for an accomplished action in an accomplished past. That is not possible in Portuguese. A sentence like "Last year I bought a car" has to be translated with the pretérito perfeito simples, see 9.1.
Conjugate the following verbs in imperfeito.