Stem-changing verbs in the Preterite

The most important things to remember about stem-changing verbs in the Preterite are:

• -Ar  (e.g., Mostrar, almorzar, pensar)  and -Er  (e.g., Perder, Tener, entender)  verbs that stem-change in the Present Tense do not stem-change in the Preterite.

• However, -Ir  stem-changing verbs (e.g. Dormir, Servir, Preferir, etc.) continue to have stem-changes BUT
• only in the 3rd person singular (él, ella, usted)  and plural (ellos, ellas, ustedes).
• They follow the same stem-changing pattern they have in the present progressive tense ("-iendo"):
•  The "O-->UE" stem-changers change to "U" as they did with the "-ing" (-iendo) form:
• Dormir:  él está durmiendo, él durmió
• And the E--->IE and the E--->I change to "I" as they did with the "-ing" (-iendo) form:
• Servir: Ella está sirviendo cerveza, ella sirvió cerveza
• When you see verbs listed in a text book or in a dictionary with vowels in a parenthesis, it shows the stem-change first in the present tense and second for all other tenses:
• Preferir (ie, i)  él prefiere, él prefirió

• Practice these forms on the Web!
• Back to the Preterite Page