Stem-changers

3 types: e -ie, e - i, and o- ue

stem vowels change in the BOOT

(nosotros, vosotros do not change)

pensar (ie) = to think

pienso	pensamos
piensas	pensáis
piensa	piensan

other e-ie stem changers:

preferir	to prefer
sentir	to be sorry
sentirse	to feel
sentarse	to sit down
divertirse	to have fun
empezar	to start
cerrar	to close
querer	to like
comenzar	to begin
entender	to understand
venir	to come