Conjugate stem changers in the preterite tense

Stem changing infinitives Stem changing infinitives are named for what they do– change in the stem. You are going to make some alteration of the stem before adding the verb endings. You will use the preterite endings you already know. The hardest part of stem changers is knowing which ones change and which ones don’t.

Two Rules for identifying Preterite Stem-Changers: 1. The infinitive must be a stem-changer in the present tense. 2. The infinitive must end in –ir.

Stem changers There are 2 different ways a stem changing infinitive can change (2 categories). -The first is ou. -This includes present tense oue.

dormir = to sleep This is a stem changer in the preterite. First separate the stem from the infinitive ending. Dorm- is the stem. Make the stem change ou New stem durm- Put into box– In the present tense, it looks like a boot. In the preterite tense, it looks like a sandal. Only the 3rd and 6th box make stem changes.

dormir = to sleep dormí

dormir = to sleep dormí dormiste

dormir = to sleep dormí dormiste durmió

dormir = to sleep dormí dormimos dormiste durmió

dormir = to sleep dormí dormimos dormiste dormisteis durmió

dormir = to sleep dormí dormimos dormiste dormisteis durmió durmieron

Stem changers The second category is ei. (This includes present tense changes eie and ei). preferir = to prefer is a stem changer. It is the same steps as dormir. *When there is more than one vowel that could possible make the change, choose the vowel closest to the verb ending.

Preferir = to prefer First separate the stem from the infinitive ending. prefer- is the stem. Make the stem change ei New stem prefir- Put into box– remember it will look like a sandal in the preterite. It will only change in the 3rd and 6th boxes.

preferir = to prefer preferí

preferir = to prefer preferí preferiste

preferir = to prefer preferí preferiste prefirió

preferir = to prefer preferí preferimos preferiste prefirió

preferir = to prefer preferí preferimos preferiste preferisteis prefirió

preferir = to prefer preferí preferimos preferiste preferisteis prefirió prefirieron

Stem changers Servir = to serve is a stem changer. It is the same steps as preferir.

servir = to serve First separate the stem from the infinitive ending. serv- is the stem. Make the stem change ei New stem sirv- Put into box– remember it will look like a sandal. In the preterite, only the 3rd and 6th boxes show change.

servir = to serve serví

servir = to serve serví serviste

servir = to serve serví serviste sirvió

servir = to serve serví servimos serviste sirvió

servir = to serve serví servimos serviste servisteis sirvió

servir = to serve serví servimos serviste servisteis sirvió sirvieron

Try these in your notes. Ellos pedir Ella repetir Nosotros sentir Usted entender Tú dormir Ellos pidieron Ella repitió Nosotros sentimos Usted entendió Tú dormiste