expresses beginning or end of an action/event

verb ends with "ed"

weather

one isolated event

was/were ________ing

mental state/physical conditions

repeated actions in the past

known time period

was o'clock

"at o'clock"

age

background descriptions of actions or events

used to + verb

ayer

"would verb" referencing the past

indicates how long, how many times the action/ event took place.

unknown time period

siempre

a veces

anteayer

a menudo

de vez en cuando

anoche

"el ______ pasado"

antes de

"cada ____"

nunca