Which Of The Following Verbs Undergoes A Stem Change In The Preterite

Preterite - stem-irresolute verbs

Spanish Grammar Preterite Tense Irregular - (e) changes to (i)

Overview

If a verb is a stem changer in the present tense, it will non stem-change in the preterit unless it is an - ir verb. No - ar or - er verbs will stem-change in the preterit.

The verbs mentir (to lie) and pedir (to request) undergo a stalk change from (e) to (i) in the "Ud./él/ella" and the "Uds./ellos/ellas" forms only. The conjugation of the verbs are shown below.

mentir (conjugation)

yo	mentí	(I told a lie)
tú	mentiste	(you told a lie)
Ud./él/ella	mintió	(he told a lie)
we every bit	mentimos	(we told a lie)
vosotros as	mentisteis	(you guys told a lie)
Uds./ellos/ellas	mintieron	(you all/they told a prevarication)

pedir (conjugation)

yo	pedí	(I requested)
tú	pediste	(yous requested)
Ud./él/ella	pidió	(you/he/she requested)
nosotros as	pedimos	(we requested)
vosotros as	pedisteis	(you lot guys requested)
Uds./ellos/ellas	pidieron	(they requested)

Let's look at a few sentences to empathize proper use:

Pedí un vaso de agua.
I asked for a glass of h2o.

Tú pediste zapatos negros.
You lot asked for black shoes.

Juan pidió un vaso de agua.
John asked for a glass of water.

Nosotros pedimos carros nuevos.
We asked for new cars.

José y Carmen pidieron una soda al mesero.
José and Carmen ordered a Soda from the server.

Other verbs that follow this pattern are:

hervir (to boil)
preferir (to prefer)
sentir (to experience)
convertir (to convert)
divertirse (to enjoy yourself)
seguir (to follow)
medir (to measure out)
repetir (to repeat)
impedir (to preclude)
reñir (to fence).