7.A Irregular in the preterite
You have already learned the preterite of two irregular verbs, ser and ir. In this section we are going to learn about other verbs that are irregular in the present that are also irregular in the preterite. There are fewer irregular verbs in the preterite than there are in the present. These verbs change in their stem and the change as follows;
Importante: the endings of all these verbs are the same as regular -er/-ir verbs except in the yo form (first person singular) and in the él/ella/usted (third person singular). None of these verbs are accented.
U-stem
I-stem
J-stem
Note: Notice that the thirds person in the plural (ellos/ellas/ustedes) form, end in -eron instead of -ieron.