“Stem-changing” verbs (e ie)
Many Spanish verbs follow a similar pattern when they are conjugated. These are called “stem-changing” verbs because there is a change to the vowel in the stem: pensar entender preferir
Although there are three types of stem-changing verbs, most follow the pattern in which the e in the stem changes to ie when the verb is conjugated. Note that stem-changing verbs may be -ar, -er or -ir, and follow the normal conjugation patterns for their type.
Stem changes occur only in the first, second, and third persons singular and the third person plural: yo quieronosotros queremos tú quieresvosotros queréis ella quiereellas quieren (This is sometimes called the “shoe” pattern.)
-ar stem-changing verbs yo pienso tú piensas él, ella, usted piensa nosotros pensamos vosotros pensáis ellos, ellas, ustedes piensan
-er stem-changing verbs yo entiendo tú entiendes él, ella, usted entiende nosotros entendemos vosotros entendéis ellos, ellas, ustedes entienden
-ir stem-changing verbs yo prefiero tú prefieres él, ella, usted prefiere Nosotros preferimos vosotros preferís ellos, ellas, ustedes prefieren
Other common stem-changing verbs have an irregular “yo” form: Tener tengotenemos tienestenéis tienetienen Venir vengovenimos vienesvenís vienevienen