Spanish Verbs in the Past (Preterito)

How to use the verbs SER and IR in the past

yo fui
tu fuiste
el/ella/Ud. fue
nosotros fuimos
vosotros fuisteis
ellos/ellas/Uds. fueron

I was
you (informal) were
he/she/you (formal) was/were
we were
you all (informal) were
they /you all (formal) were

yo fui
tu fuiste
el/ella/Ud. fue
nosotros fuimos
vosotros fuisteis
ellos/ellas/Uds. fueron

I went
you (informal) went
he/she/you (formal) went
we went
you all (informal) went
they /you all (formal) went

How do you know which verb is meant in a particular sentence???
Como se sabe cual verbo es el correcto en cada frase?

You have to read the rest of the sentence to help figure it out.