There are only two types of stem changes in the preterite tense. The
changes are E → I and O → U. Although some verbs have stem changes, they all have the same endings as the regular preterite verbs do. These stem-changes
are only in the third person singular (el/ella/usted) and third person plural
(ellos/ellas/ustedes). The change happens on the vowel next to the last syllable.
Verbs that change from E → I:
LISTEN
Mentir
to lie Yo mentí Tú mentiste Él/ella mintió Usted mintió Nosotros mentimos Ellos/ellas mintieron Ustedes mintieron
Seguir
to follow Yo seguí Tú seguiste Él/ella
siguió Usted siguió Nosotros
seguimos Ellos/ellas siguieron Ustedes siguieron
Verbs that change from O → U:
Dormir
to sleep Yo dormí Tú dormiste Él/ella durmió Usted durmió Nosotros dormimos Ellos/ellas durmieron Ustedes durmieron
Morir
to die Yo morí Tú moriste Él/ella murió Usted murió Nosotros morimos Ellos/ellas murieron Ustedes murieron
MORE STEM-CHANGING VERBS IN THE PRETERITE TENSE ...
More verbs that change from E → I
sentir to
feel servir to serve perseguir
to chase competir to compete preferir to prefer pedir
to ask for repetir to repeat sugerir to suggest
requerir to
request reír to laugh sonreír
to smile freír to fry despedir to say goodbye vestir
to dress divertirse to have fun
