Short Answer: Conjugate the verb preferir in all forms in the Present Tense. What takes place in the conjugation that makes this verb a stem-changing verb?

The verb "preferir" is conjugated in the Present Tense as follows:

• Yo prefiero
• Tú prefieres
• Él/Ella/Usted prefiere
• Nosotros/Nosotras preferimos
• Vosotros/Vosotras preferís
• Ellos/Ellas/Ustedes prefieren

"Preferir" is a stem-changing verb because it undergoes a vowel change in the stem in all forms except for the nosotros and vosotros forms. Specifically, the e in the stem changes to ie in the conjugated forms: "prefiero," "prefieres," "prefiere," and "prefieren."