Completed vs Ongoing Actions | Portuguese (Portugal) Grammar

Portuguese has two main past tenses, and learners from English often assume they are interchangeable. They are not. The pretérito perfeito simples and the pretérito imperfeito describe the same past time from two different angles. Choosing between them is not about when the action happened, but about how you see it -- as a finished event or as an open situation.

The core distinction in one sentence

Preterite = closed box. Imperfect = open window.

The preterite puts the action inside a box with a lid -- it started, it ended, it is done. The imperfect opens a window onto a situation and leaves it open -- no beginning, no end, just the middle.

Ontem fui ao cinema.

Yesterday I went to the cinema.

Quando era criança, ia ao cinema aos sábados.

When I was a child, I used to go to the cinema on Saturdays.

Both sentences are about going to the cinema in the past. Both are true statements. But fui zooms in on one specific trip -- it happened once, it is finished. Ia zooms out to describe a habit that stretched across years without pinpointing any single trip.

The snapshot vs the movie

A useful metaphor: the preterite is a snapshot and the imperfect is a movie clip.

A snapshot captures one frozen moment. You know when the shutter clicked. There is a clear before and after.

A movie clip shows things in motion. You might not know exactly when it started or when it will end -- you just see the action unfolding.

A Joana entrou na sala e sentou-se.

Joana walked into the room and sat down.

Two snapshots in quick succession. She walked in; she sat down. Both bounded, both finished.

A Joana falava ao telefone enquanto eu escrevia o email.

Joana was talking on the phone while I was writing the email.

Two movie clips running in parallel. Neither action has a visible start or end -- we simply see them unfolding at the same time.

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When you are about to use a past tense, ask yourself: do I want to show this action as something that happened and finished (snapshot = preterite), or as something that was going on or used to go on (movie = imperfect)?

Side-by-side pairs

The clearest way to feel the difference is to see the same verb in both aspects:

Preterite (bounded)	Imperfect (open)
Ontem jantei às oito. Yesterday I had dinner at eight.	Antigamente jantávamos às oito. We used to have dinner at eight.
Morei em Lisboa dois anos. I lived in Lisbon for two years.	Quando morava em Lisboa, apanhava o comboio todas as manhãs. When I lived in Lisbon, I'd take the train every morning.
Estive doente na semana passada. I was ill last week.	Estava doente, por isso não fui à festa. I was ill, so I didn't go to the party.
Tive um cão quando era pequeno. I had a dog when I was little.	Tinha um cão que ladrava a toda a gente. I had a dog that barked at everybody.

Notice how in the preterite column, every action has an implied boundary -- two years ends, last week ends, the dog belonged to me for a defined period. In the imperfect column, the same situations are left open. Morava em Lisboa doesn't tell you when it started or ended; it just gives you the backdrop for the habitual train-taking.

Aspect is in your head, not in the verb

Here is the tricky part: the same event in the real world can be described either way, depending on how you choose to view it. The verb form reflects the speaker's perspective, not a property of the action itself.

O meu avô foi professor durante trinta anos.

My grandfather was a teacher for thirty years.

O meu avô era professor quando o conheci.

My grandfather was a teacher when I met him.

Both are about the grandfather being a teacher. The first closes the box: thirty years, now over -- foi. The second opens the window onto a state that was true at the moment of meeting -- era. Neither is more correct; they simply highlight different facets.

Vivi em Coimbra cinco anos e adorei.

I lived in Coimbra for five years and loved it.

Vivia em Coimbra e trabalhava numa livraria.

I was living in Coimbra and working in a bookshop.

Again, the first wraps the whole experience up; the second hands you two parallel ongoing situations.

Habitual past -- the biggest trap for English speakers

English has no dedicated habitual past tense. We use the simple past for both "I went to the gym yesterday" (one event) and "I went to the gym every day when I was twenty" (habit). Portuguese does not accept that overlap. Habits in the past require the imperfect.

Quando vivia em Inglaterra, ia ao ginásio todos os dias.

When I lived in England, I went to the gym every day.

An English speaker's first instinct is to translate "went" as fui -- but fui means I went (once). For every day, Portuguese demands ia.

Em miúdo, comia sandes de queijo ao lanche.

As a kid, I'd eat cheese sandwiches for my afternoon snack.

English "would" or "used to" is often (but not always) a reliable cue that the imperfect is correct in Portuguese. If you can reword an English sentence as "used to X," you almost certainly want the imperfect.

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The English phrase "used to" is a nearly foolproof imperfect trigger. If it fits in English, use the imperfect in Portuguese: used to live there → vivia lá, used to smoke → fumava, used to call every Sunday → ligava todos os domingos.

Duration expressions can go either way

Many learners are told that "time expressions with a duration always take the preterite." This is false. Duration is compatible with both aspects, depending on whether the speaker is closing or opening the box.

Esperei uma hora no aeroporto.

I waited one hour at the airport.

Esperava há uma hora quando ela finalmente chegou.

I had been waiting for an hour when she finally arrived.

The first encloses the wait: one hour, beginning to end, over. The second presents the wait as the ongoing backdrop against which she finally arrived is the punctual event. Both sentences contain the phrase uma hora, yet the aspect is different.

Durante dois anos, estudei violino.

For two years, I studied violin.

Here durante dois anos marks a completed period -- I did this, it lasted two years, and it's wrapped up. Preterite wins.

States of mind and body

Verbs describing mental or physical states -- estar, ter (as in ter fome, ter medo), querer, saber, pensar, sentir-se -- lean heavily towards the imperfect, because mental states are usually ongoing. Using the preterite with these verbs often shifts the meaning in a subtle but important way.

Eu tinha fome, por isso comprei uma sandes.

I was hungry, so I bought a sandwich.

Tinha fome is a state that was true across the relevant moment. Comprei is the action that resulted. Mixing them up (saying ~~Tive fome, por isso comprei~~) sounds jarring to a native ear -- it suggests the hunger started and ended in a defined pulse, which is odd for a feeling.

Ontem estava cansado e fui deitar-me cedo.

I was tired yesterday and went to bed early.

Estava cansado describes the background mood; fui deitar-me is the action.

Why English speakers get this wrong

The fundamental mismatch is that English packs two meanings into a single simple past form. "I ate" can mean:

I ate (once, at a specific moment) → comi
I used to eat / I would eat (habitually) → comia
I was eating (in progress) → estava a comer or comia

Portuguese forces you to pick one. There is no neutral past. Every time you use a past-tense verb, you are making an aspectual choice -- closed box or open window.

Spanish learners, take note: the preterite vs imperfect distinction in European Portuguese works almost identically to Spanish. Most of your Spanish instincts carry over cleanly. But watch out -- Portuguese does not use the compound tenho falado the way Spanish uses he hablado. For a single completed action, EP uses the simple preterite, full stop. See Forming the Pretérito Perfeito Composto for why.

Common mistakes

❌ Quando era criança, fui à praia todos os verões.

Incorrect -- 'todos os verões' is habitual, needs imperfect.

✅ Quando era criança, ia à praia todos os verões.

When I was a child, I went to the beach every summer.

❌ O meu pai foi alto e tinha barba.

Incorrect -- mixing aspects for description; both should be imperfect.

✅ O meu pai era alto e tinha barba.

My father was tall and had a beard.

❌ Ontem comia uma bifana no Martinho.

Incorrect as narration -- 'ontem' with a single event needs the preterite.

✅ Ontem comi uma bifana no Martinho.

Yesterday I had a pork sandwich at Martinho's.

❌ Quando o telefone tocou, eu dormi.

Incorrect -- the ongoing action (sleeping) interrupted by the call needs imperfect.

✅ Quando o telefone tocou, eu dormia.

When the phone rang, I was sleeping.

❌ Morei em Lisboa e a cidade foi linda.

Incorrect -- describing the city's character requires the imperfect.

✅ Morei em Lisboa e a cidade era linda.

I lived in Lisbon and the city was beautiful.

Key takeaways

The preterite closes the box: bounded, finished, punctual. The imperfect opens the window: ongoing, habitual, descriptive.
Same event, different angle: the choice reflects your perspective, not a property of the action.
English "used to" and "would (habitually)" almost always map to the imperfect.
Descriptions of people, places, weather, and mental states lean strongly imperfect.
Ongoing background action + punctual interruption = imperfect + preterite.

From here, move on to Preterite and Imperfect in Narration to see how both tenses work together in story-telling, and Time Expressions as Clues for the words that signal each tense.