Preterite Stem Changing Verbs
-ar and -er verbs that change their stem in the present tense do not change in the preterite. They are conjugated just like other regular preterite verbs, using the regular endings.
cerrar
³¦±ð°ù°ùé
cerraste
³¦±ð°ù°ùó
cerramos
cerrasteis
cerraron
entender
±ð²Ô³Ù±ð²Ô»åÃ
entendiste
±ð²Ô³Ù±ð²Ô»å¾±Ã³
entendimos
entendisteis
entendieron
-ir verbs that change their stem in the present tense do change in the preterite, but in a different way. They change e:i and o:u in the third person, singular and plural.
preferir
±è°ù±ð´Ú±ð°ùÃ
preferiste
prefi°ù¾±Ã³
preferimos
preferisteis
prefirieron
dormir
»å´Ç°ù³¾Ã
dormiste
du°ù³¾¾±Ã³
dormimos
dormisteis
durmieron