Stem Changing Verbs "E">"Ie"
The main form of the verb is called the infinitive. The infinitive consists of two parts: the ending and the stem. The ending is the last two letters. There are only three different endings: -ar, -er, and -ir. The stem is everything else, except the ending.
hablar: ending = ar, stem = habl
comer: ending = er, stem = com
vivir: ending = ir, stem = viv
Some spanish verbs are called stem-changers because when they are conjugated, the stem changes in a predictable way. In one group of stem-changing verbs, the letter e in the stem changes to ie in all but the nosotros and vosotros forms. This particular type of stem-changing verb is found in all three verb types.
cerrar
yo cierro
tú cierras
él, ella, Ud. cierranosotros/as cerramos
vosotros/as cerráisellos, ellas, Uds. cierran
For a more complete discussion of verbs that change e:ie click here.
Here are some common e:ie stem-changing verbs.
acertar
to manage toadvertir
to alertatender
to attend toatravesar
to crosscalentar
to heatcerrar
to closecomenzar
to beginconfesar
to confessconvertir
to convertdefender
to defenddespertar
to wake updivertir
to amuseempezar
to beginencender
to lightentender
to understandenterrar
to buryfregar
to scrubherir
to injurehervir
to boilmentir
to liemerendar
to have lunchnegar
to denypensar
to thinkperder
to losepreferir
to preferquerer
to wantregar
to watersugerir
to suggesttemblar
to trembletender
to spread overtropezar
to stumble onverter
to spill