Irregular Spanish verbs (Present tense) 1

Three types of present tense irregularity — Spanish irregular present tenses fall into three main groups: (1) yo-form only irregulars (go-verbs): hacer → hago, poner → pongo, traer → traigo; (2) stem-changing verbs (affect all but nosotros/vosotros): poder → puedo, querer → quiero; (3) completely irregular: ser, ir, estar, saber, dar.

Stem changes: e→ie, o→ue, e→i — Stem-changing verbs change the stressed vowel of the stem in all forms except nosotros/vosotros: e → ie: querer → quiero, pensar → pienso. o → ue: poder → puedo, dormir → duermo. e → i: pedir → pido, repetir → repito.

Saber vs conocer — both mean to know — Saber (yo form: sé) = to know a fact or how to do something: Sé nadar. Sé que llega tarde. Conocer (yo form: conozco) = to be acquainted with a person, place, or thing: Conozco a María. ¿Conoces Barcelona?. Mixing these up is one of the most common intermediate-level errors.