# Stem change o → ue (poder, volver, dormir)

> id: conjugation.present.stem-o-ue · category: conjugation · depth: standard · levels: A1, A2 · review: internally_reviewed

**Summary.** The stressed stem vowel o becomes ue in the four boot forms: puedo, puedes, puede, pueden — but podemos, podéis, vos podés.

Same boot logic as e → ie, applied to o: when the stem syllable is stressed, o opens into ue. Poder → puedo; volver → vuelvo; dormir → duermo; contar → cuento.

Nosotros and vosotros keep the plain o (podemos, volvéis), and so does vos (vos podés, vos dormís), because their endings carry the stress.

For -ir verbs of this family (dormir, morir), the o also raises to u in the preterite third person (durmió, murieron) and the gerund (durmiendo) — covered by the third-person stem change rule.

## Examples
- No puedo hoy. — I can't today.
- ¿A qué hora vuelves? — What time do you come back?
- Dormimos ocho horas. — We sleep eight hours. *(No diphthong in nosotros.)*

Related: conjugation.present.stem-e-ie, conjugation.present.stem-u-ue, conjugation.preterite.stem-third-person

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