Stem-Changing Verbs (Oh, the HORROR!!)

There is a large class of Spanish verbs that are stem-changing.  Although they are irregular as far as not following the regular pattern of conjugation, they are technically in a class of verbs all to themselves. 

As you already know, when conjugating verbs we drop the infinitive ending but keep the root (or stem) upon which we add the final conjugated suffix.  With a stem-changing verb, the root is altered to form a new vocal sound, with the exception of conjugations in the nosotros and vosotros forms.

A common stem-change is (oàue) which can be included in any verb (-ar, -er, or –ir).  Our first stem-changing verb we’ll look at is poder (to be able to, “can”), which is one of the most useful verbs to have in your arsenal.  It’s an (oàue) verb, which means the o in its prefix will be replaced by the diphthong pair ue in all but the nosotros and vosotros conjugations like so:

	Singular	Plural
1st Person	(yo) puedo	(nosotros, nosotras) podemos
2nd Person	(tú) puedes	(vosotros, vosotras) podéis
3rd Person	(él, ella, Ud.) puede	(ellos, ellas, Uds.)  pueden

Here are other (oàue) verbs to learn: 

Verb	Root	New Root	Tú Form
volver (to return, to go back)	volv-	vuelv-	vuelves
devolver (to return an object)	devolv-	devuelv-	devuelves
soler (to be used to)	sol-	suel-	sueles
torcer (to twist)*	torc-	tuerc-	tuerces
almorzar (to eat lunch)	almorz-	almuerc-	almuerces
contar (to tell, to count)	cont-	cuent-	cuentas
costar (to cost)	cost-	cuest-	cuestas
demostrar (to show,demonstrate)	demostr-	demuestr-	demuestras
doler (to ache, to hurt)	dol-	duel-	dueles
encontrar (to find)	encontr-	encuentr-	encuentras
envolver (to wrap)	envolv-	envuelv-	envuelves
mostrar (to show)	mostr-	muestr-	muestras
recordar (to remember)	record-	recuerd-	recuerdas
resolver (to resolve, to solve)	resolv-	resuelv-	resuelves
volar (to fly)	vol-	vuel-	vuelas

Another common stem change is (eàie). Here are a lot of verbs that follow this pattern:

Verb	Root	New Root	Tú Form
querer (to want, to love)	quer-	quier-	quieres
pensar (to think)	pens-	piens-	piensas
ascender (to go up, to ascend)	ascend-	asciend-	asciendes
atravesar (to cross)	atraves-	atravies-	atraviesas
cerrar (to close)	cerr-	cierr-	cierras
comenzar (to begin)	comenz-	comienz-	comienzas
confesar (to confess)	confes-	confies-	confiesas
defender (to defend)	defend-	defiend-	defiendes
descender (to descend)	descend-	desciend-	desciendes
doler (to hurt, to cause pain)	dol-	duel-	dueles
empezar (to begin)	empez-	empiez-	empiezas
encender (to light, ignite)	encend-	enciend-	enciendes
encerrar (to enclose)	encerr-	encierr-	encierras
entender (to understand)	entend-	entiend-	entiendes
gobernar (to govern)	gobern-	gobiern-	gobiernas
perder (to lose)	perd-	pierd-	pierdes
quebrar (to break)	quebr-	quiebr-	quiebras
recomendar (to recommend)	recomend-	recomiend-	recomiendas

Some –ir verbs have an (eài) stem change.  The verb pedir (to ask for) is a very common example. 

	Singular	Plural
1st Person	(yo) pido	(nosotros, nosotras) pedimos
2nd Person	(tú) pides	(vosotros, vosotras) pedís
3rd Person	(él, ella, Ud.) pide	(ellos, ellas, Uds.)  piden

                                                                                                         

Here are other verbs that pattern like pedir: 

Verb	Root	Yo Form
conseguir (to get)	consegu-	consigo
despedir (to fire)	desped-	despido
impedir (to prevent)	imped-	impido
medir (to measure)	med-	mido
servir (to serve)	serv-	sirvo
seguir (to continue, to follow)	segu-	sigo
repetir (to repeat)	repet-	repito
vestir (to dress)	vest-	visto

Using Two Verbs in a Clause

If you recall, there a couple of verb phrases that you’ve learned (i.g. ir a + infinitive verb, tener que + infinitive verb) that use two verbs, one of which is left in the infinitive.  The verb poder can be used in this way.

Puedo patinar.  I can skate.

Puedes cocinar.  You can cook.

El gerente puede trabajar.  The manager can work.

Podemos aprender.  We can learn. 

Podéis comprar unos juguetes.  You can all buy some toys.

Pueden venir aquí.  They can come here.