This lesson is for verbs whose preterite differs from the regular pattern through a stem or spelling change, while still retaining recognizable preterite endings.
Spelling changes
In the yo form, -car changes to -qué (buscar → busqué), -gar to -gué, and -zar to -cé.
A changed-form example
buscar in Pretérito
Stem changes in the third person
An -ir verb that changes its stem in the present changes it again in él/ella/usted and ellos/ellas/ustedes: e → i and o → u. The other four forms keep the plain stem.
| Verb | él/ella/ud. | ellos/uds. |
|---|---|---|
| pedir | pidió | pidieron |
| sentir | sintió | sintieron |
| dormir | durmió | durmieron |
i → y
Where the stem ends in a vowel, the i of -ió and -ieron becomes y: leer → leyó, leyeron; oír → oyó, oyeron; construir → construyó, construyeron.