Stem Changers in the Preterite Tense

If a verb is a stem changer in the present tense, it will not stem change in the preterite unless it is an – ir verb. No – ar or – er verbs will stem change in the preterite.

Stem-changing verbs ending in -ir

An –ir verb that stem changes in the present tense will stem change in the preterite but only in the third person forms ( él, ella, usted, ellos, ellas, and ustedes). Any –ir verb that stem changed o>ue will stem change o>uin the preterite in the third person forms. Table 1 demonstrates the preterite patterns for all –ir verbs that stem‐changes o>ue in the present tense. The verb dormir (to sleep) is conjugated exactly the same in both tenses.

There are several – ir verbs that stem change e>ie in the present tense. Any – ir verb that stem changes e>ie in the present tense, will stem change e>i in the preterite but only in the third person forms (él, ella, usted, ellos, ellas, ustedes). Table 2, which conjugates the verb mentir (to tell a lie), demonstrates the preterite patterns for all –ir verbs that stem change e>ie in the present tense.

Here are some common – ir verbs that are all conjugated like mentir in the preterite tense:

If an – ir verb stem changes e>i in the present tense, it will also stem change e>i in the preterite, but only in the third person forms ( él, ella, usted, ellos, ellas, ustedes). Table 3, which conjugates the verb pedir (to request), demonstrates the preterite patterns for all ‐ir verbs that stem change e>i in the present tense.

Here are some common verbs that are all conjugated like pedir in the preterite tense: