Answer:
Ayer yo prometí llevar a mi sobrino al cine.
Explanation:
Ayer yo prometí llevar a mi sobrino al cine. This means in English: yesterday I promised my nephew I'd take him to the movies. In Spanish conjugation changes according to the person that accompanies the verb. In this case, the verb is in the first person of the singular, so it is "prometí". This is de verb "prometer" conjugation:
Yo: prometí
Tú: prometiste
Él/ella: prometió
Nosotros: prometimos
Ustedes: prometieron
Ellos: prometieron
