Preterite Orthographic Changing Verbs

The following changes occur in the yo form only:

Verbs that end in -gar change g to gu
Verbs that end in -car change c to qu
Verbs that end in -zar change z to c

Examples:

jugué (jugar)
busqué (buscar)
almorcé (almorzar)

Here are some examples of common verbs in this category:

jugar
llegar
pagar
rogar

aparcar
buscar
clasificar
tocar

almorzar
comenzar
empezar
organizar

For verbs that end in -aer, -eer, -oír, and -oer, the él,/ella/usted form uses the ending (rather than ió) and the third person plural uses the ending yeron (rather than ieron). The remaining forms gain a written accent over the letter i.

Example: creer

creí
creíste
cre
creímos
creísteis
creyeron

Other verbs like creer include:

caer
leer
oír
poseer
proveer
roer

Exceptions to this rule include:

traer
atraer
distraer

Verbs that end in -uir change in the same way, but the written accent over the letter i only occurs in the yo form.

Example: huir

huí
huiste
hu
huimos
huisteis
huyeron

Other verbs like huir include:

construir
contribuir
destruir
fluir
incluir
influir