Breakdown of El edificio estaba temblando a las tres.
las
the (feminine plural)
estar
to be (location/state)
a
to
el edificio
the building
Questions & Answers about El edificio estaba temblando a las tres.
Why do we use estaba temblando here instead of a simple past tense?
This sentence uses the past continuous tense. By combining estaba (the imperfect form of estar, meaning 'was') with temblando (the '-ing' form of the verb), it emphasizes that the shaking was currently in progress at that exact moment. You could also just say temblaba, but estaba temblando paints a much more vivid picture of the ongoing action.
Doesn't mentioning a specific time like 'at three o'clock' usually mean we should use the preterite tense?
Often, yes! If an action started or finished exactly at three o'clock (like 'The earthquake started at three'), you use the preterite. However, this sentence describes what was already happening in the background when the clock struck three. Because the shaking was an ongoing state at that moment, rather than a completed event, we use the imperfect estaba.
What is the infinitive (dictionary form) of temblando?
Why do we need las in a las tres?