Pretérito, imperfecto, y presente perfecto

Regular -AR endings

é, aste, ó, amos, aron

Regular -ER/IR endings

í, iste, ió, imos, ieron

When to use pretérito?

To talk about actions in the past that had a starting and ending point

When to use imperfecto?

To talk about actions in the past that had a starting point but no definitive ending

When to use presente perfecto?

To talk about recent/past events that happened at an indefinite time

Dormir (pretérito) (o → u)

dormí, dormiste, durmió, dormimos, durmieron

Morir (pretérito) (o → u)

Morí, moriste, murió, morimos, murieron

Pedir (pretérito) (e → i)

Pedí, pediste, pidió, pedimos, pidieron

Preferir (e → i)

Preferí, preferiste, prefirió, preferimos, prefirieron

Seguir (e → i)

Seguí, seguiste, siguió, seguimos, siguieron

Competir (e → i)