Types of Irregular Preterite Verbs
Irregular verbs in the preterite can be categorized into a few different types.
'-Ir' stem-changing verbs have a stem-change in the present as well as a stem-change in both the preterite third-person singular and third-person plural forms. This means that they are completely regular in the preterite in the yo, tú, nosotros/as, vosotros/as forms, but not in the él, ella, usted, ellos, ellas, ustedes forms.
U-stem verbs have a stem-change that throws the letter u into the mix.
I-stem verbs have a stem-change that throws the letter i into the mix.
J-stem verbs will add a j or change the letter c to a j when conjugated.
Ir, ser, and dar are special cases that we'll go over together.