# Stem change e → ie (pensar, querer, sentir)

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

**Summary.** The stressed stem vowel e becomes ie in yo, tú, él/ella/usted, and ellos/ellas/ustedes — never in nosotros, vosotros, or vos.

In many verbs, the last e of the stem turns into ie whenever that syllable carries the stress: pensar → pienso, piensas, piensa, piensan — but pensamos, pensáis, because there the stress falls on the ending.

This 'boot' pattern (the four changing forms draw a boot shape in a conjugation table) applies across -ar, -er, and -ir verbs: querer → quiero, sentir → siento, empezar → empiezo.

Vos forms never diphthongize, because vos endings are stressed: vos pensás, vos querés, vos sentís. For -ir verbs of this family, the e also raises to i elsewhere (preterite third person, gerund, some subjunctive forms) — see the third-person stem change rule.

## Examples
- Pienso en ti. — I think about you.
- ¿Quieres venir con nosotros? — Do you want to come with us?
- Pensamos lo mismo. — We think the same. *(No diphthong: stress on the ending.)*

Related: conjugation.present.stem-o-ue, conjugation.present.stem-e-i, conjugation.preterite.stem-third-person

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