6.C Preterite stem-changing
The preterit, unlike the present there are no stem changing verbs in verbs that end in -ar and -er. They do have the accents the same as the regular verbs in the preterit.
There are only a couple of stem changing verbs that end in -ir, but only in the third person singular and third person plural.
Pedir | Servir | Morir | |
Yo | pedí | serví | morí |
Tú | pediste | serviste | moriste |
El/ella/usted | pidió | sirvió | murió |
Nosotros/as | pedimos | servimos | morimos |
Vosotros/as | pedisteis | servisteis | moristeis |
Ellos/ellas/ustedes | pidieron | sirvieron | murieron |