Stem-changing verbs AKA Boot verbs
-The infinitive is the basic, unconjugated form of a verb, sometimes called the name of the verb. -In English the infinitive is to + verb: to begin, to want, to prefer, etc.
The Spanish infinitive is a single word with one of the following endings: -ar, -er, or -ir: empezar, querer, preferir We usually learn Spanish verbs in the infinitive, since that is what you start with in order to conjugate them.
Verbs have two parts the ending and the stem
The ending is the last two letters of a verb in infinitive. It should be -ar -er or -ir Querer empezar Preferir
ending The stem is what is left after dropping the ending (last two letters of the infinitive) empez ar stem
quer er stem prefer ir stem
The last vowel of the stem will change. In this type of stem changing verb e will change to ie quere er
Verbs that change e→ie
D quieroYo quere Nosotros Túquieres Vosotros quer éis Él Ella quiere Ellos Ellas quieren Ud.quie re Uds.quieren mos Querer
D pref ieroYo preferi Nosotros Túprefieres Vosotros prefer ís Él Ella prefiere Ellos Ellas prefieren Ud.prefie re Uds.prefieren mos Preferir
D emp ie z oYo empeza Nosotros Túempiezas Vosotros empez áis Él Ella empieza Ellos Ellas empiezan Ud.empie za Uds.empiezan mos Empezar