In the present tense conjugation of the verb "preferir," it undergoes a stem change from "e" to "ie" in all forms except for the nosotros and vosotros forms. Here’s how it is conjugated:
- Yo prefiero
- Tú prefieres
- Él/Ella/Usted prefiere
- Nosotros/Nosotras preferimos
- Vosotros/Vosotras preferís
- Ellos/Ellas/Ustedes prefieren
The stem-changing occurs because, in the present tense, the vowel "e" in the stem (prefer-) changes to "ie" in all singular forms and the third person plural. This is a characteristic of certain -ir verbs in Spanish that experience this type of alteration in their conjugation.