Introduction

Ser means “to be”, and this page covers exactly one thing: ser in the pretérito perfeito. The pretérito perfeito is the tense Portuguese speakers reach for when they talk about one finished action in the past, especially in conversation. On this page you will find the full pretérito perfeito table for ser, how the tense is formed for this verb, the situations where it is used, how it differs from the pretérito imperfeito, worked examples, the mistakes learners make most often, an eight-question quiz with explained answers, and answers to the questions students ask about ser in the pretérito perfeito. It is the verb of identity, description, origin and time: you use it to say who someone is, what something is like, where someone comes from and what time it is. It shares its pretérito perfeito — fui, foste, foi, fomos, fostes, foram — with ir, so context tells you whether fui means “I was” or “I went”. Learn ser and estar together, because the choice between them is the first decision in almost every Portuguese sentence. For example: “Ele foi professor ontem.” — “He was a teacher.” Everything on this page uses the forms of ser exactly as they are conjugated in the pretérito perfeito, so you can trust every form you see here.

Ser in the Pretérito perfeito — full table

Person Form
eu fui
tu foste
ele/ela foi
nós fomos
vós fostes
eles/elas foram
Gerund: sendo · Past participle: sido
The gerund is sendo, which you use with estar to say what is happening at the same time as the main action: “Sendo professor, aprendo muito.” — “While being a teacher, I learn a lot.” The past participle is sido, which you use with ter in the perfect tenses: tenho sido is the pretérito perfeito composto, used for a completed action. Keep both forms in mind as you read the examples below, because the pretérito perfeito is only one part of how ser is used.
Pronunciation is not listed on this page: the verified tables do not include IPA for ser, so no pronunciation is given rather than an invented one.

How the pretérito perfeito of ser is formed

The pretérito perfeito of ser has six forms: eu fui, tu foste, ele foi, nós fomos, vós fostes, eles foram. The participle is given here in the masculine singular form, exactly as it appears in the verified dump; agreement with the subject is a separate step that depends on the sentence, not on the verb table. ser is irregular in the pretérito perfeito, so the six forms have to be learnt as a set instead of derived from the infinitive. The stem changes completely in this tense, and no rule predicts the forms — learn them whole, starting with eu and ele, the two forms you will use most.

Two things about the pretérito perfeito of ser are worth noticing. First, it is the tense of finished events with a clear result, so it pairs naturally with time words such as ontem, esta semana and no ano passado — those time words are your best clue when you are choosing a tense. Second, it is a simple tense, built from one word, unlike the pretérito perfeito composto, which needs ter plus the participle sido: tenho sido. When the action is one finished event, reach for the simple form first.

Because the pretérito perfeito of ser is one word per person, it is cheap to learn once the six forms are fixed. Learn them in order — eu, tu, ele, nós, vós, eles — and say each one with a time word, so the tense and its time words are learnt together.

When to use the pretérito perfeito of ser

The pretérito perfeito is not a single-purpose tense. Below are the five situations where you will use ser in the pretérito perfeito most often. Each one comes with a real example, so read the rule, then say the example out loud.

1. One finished action

The pretérito perfeito describes a single action that is finished, especially in spoken Portuguese. When the action has a clear end, the pretérito perfeito is the natural choice. Example: “Eu fui professor ontem.” — “I was a teacher.”

2. Recent events

Use the pretérito perfeito for things that happened recently — today, this week, this morning — where the result is still visible in the present. Example: “Ele foi professor ontem.” — “He was a teacher.”

3. A sequence of events

When you tell what happened first, second and third, each step takes the pretérito perfeito. The tense moves the story forward one finished action at a time. Example: “Nós fomos professor ontem.” — “We were a teacher.”

4. An experience in your life

Use the pretérito perfeito for things you have done in your life, with or without a time expression. It is the tense of experience as much as of yesterday. Example: “Tu foste professor ontem.” — “You were a teacher.”

5. News and results

When you report news or a result, the pretérito perfeito carries it: something happened, and now the situation is different. The result matters more than the process. Example: “Eles foram professor ontem.” — “They were a teacher.”

Pretérito Perfeito vs Pretérito Imperfeito: how to choose

The closest tense to the pretérito perfeito is the pretérito imperfeito, and learners mix them up constantly. The rule is simple: the pretérito perfeito describes one finished action, while the pretérito imperfeito describes an ongoing or habitual action in the past, or the background of a scene. The three pairs below use the same verb, so the only thing that changes is the time frame — and with it, the tense. Notice how the pretérito perfeito sentences use words such as ontem or esta semana, while the pretérito imperfeito sentences use antigamente or todos os dias.

  • Pretérito Perfeito: “Ele foi professor ontem.” — “He was a teacher”
  • Pretérito Imperfeito: “Ele era professor antigamente.” — “He used to be a teacher”
  • The pretérito perfeito sentence is one finished event; the pretérito imperfeito sentence is an ongoing or habitual past action. Ontem points to the pretérito perfeito, antigamente points to the pretérito imperfeito.
  • Pretérito Perfeito: “Eu fui professor ontem.” — “I was a teacher”
  • Pretérito Imperfeito: “Eu era professor antigamente.” — “I used to be a teacher”
  • The pretérito perfeito sentence is one finished event; the pretérito imperfeito sentence is an ongoing or habitual past action. Ontem points to the pretérito perfeito, antigamente points to the pretérito imperfeito.
  • Pretérito Perfeito: “Tu foste professor ontem.” — “You were a teacher”
  • Pretérito Imperfeito: “Tu eras professor antigamente.” — “You used to be a teacher”
  • The pretérito perfeito sentence is one finished event; the pretérito imperfeito sentence is an ongoing or habitual past action. Ontem points to the pretérito perfeito, antigamente points to the pretérito imperfeito.

Example sentences: ser in the pretérito perfeito

Read these eight sentences out loud. They cover all six persons, so by the end you will have seen every form in the table used in a real sentence. Pay attention to the words around the verb — the time expressions and the objects — because those are what make each sentence sound natural.

  1. “Eu fui professor ontem.” — “I was a teacher”
  2. “Tu foste professor ontem.” — “You were a teacher”
  3. “Ele foi professor ontem.” — “He was a teacher”
  4. “Nós fomos professor ontem.” — “We were a teacher”
  5. “Vós fostes professor ontem.” — “You were a teacher”
  6. “Eles foram professor ontem.” — “They were a teacher”
  7. “Eu fui professor ontem.” — “I was a teacher”
  8. “Ele foi professor ontem.” — “He was a teacher”

Common mistakes

These are the errors learners actually make with this verb in this tense. Each one shows the wrong version, the right version, and why the correction matters.

  • Wrong: “Eu sou professor ontem.” Right: “Eu fui professor ontem.” Why: Ontem points to the past, so the present is wrong here. Use the pretérito perfeito fui for a finished action yesterday.
  • Wrong: “Eu era professor ontem.” Right: “Eu fui professor ontem.” Why: The pretérito imperfeito describes an ongoing or habitual past action, not one finished event. For a single finished action yesterday, use the pretérito perfeito fui.
  • Wrong: “Eu foste professor.” Right: “Eu fui professor ontem.” Why: The eu form is fui, not foste. foste is the tu form. Match the verb to the subject every time.
  • Wrong: “Eu ser professor.” Right: “Eu fui professor ontem.” Why: The infinitive ser never takes a subject and never forms a past tense on its own. After eu you need the conjugated pretérito perfeito form fui.

Quiz: test yourself

Choose the correct answer for each question, then check the answer key. Every answer is explained, so a wrong answer still teaches you something.

  1. What is the eu form of ser in the Pretérito perfeito?

    • A) foste
    • B) fui
    • C) foi
    • D) fomos

  2. What is the tu form of ser in the Pretérito perfeito?

    • A) fui
    • B) foi
    • C) foste
    • D) fomos

  3. What is the ele/ela form of ser in the Pretérito perfeito?

    • A) fui
    • B) foste
    • C) fomos
    • D) foi

  4. What is the nós form of ser in the Pretérito perfeito?

    • A) fomos
    • B) fui
    • C) foste
    • D) foi

  5. What is the vós form of ser in the Pretérito perfeito?

    • A) fui
    • B) fostes
    • C) foste
    • D) foi

  6. What is the eles/elas form of ser in the Pretérito perfeito?

    • A) fui
    • B) foste
    • C) foram
    • D) foi

  7. What is the eu form of ser in the Pretérito perfeito?

    • A) foste
    • B) foi
    • C) fomos
    • D) fui

  8. What is the tu form of ser in the Pretérito perfeito?

    • A) foste
    • B) fui
    • C) foi
    • D) fomos

Answer key

  1. B) fui — the correct form is fui. The other options are other forms of the same verb.
  2. C) foste — the correct form is foste. The other options are other forms of the same verb.
  3. D) foi — the correct form is foi. The other options are other forms of the same verb.
  4. A) fomos — the correct form is fomos. The other options are other forms of the same verb.
  5. B) fostes — the correct form is fostes. The other options are other forms of the same verb.
  6. C) foram — the correct form is foram. The other options are other forms of the same verb.
  7. D) fui — the correct form is fui. The other options are other forms of the same verb.
  8. A) foste — the correct form is foste. The other options are other forms of the same verb.

Frequently asked questions

What does ser mean in English?

ser means “to be”. It is a irregular -er verb.

How is the pretérito perfeito of ser formed?

The six pretérito perfeito forms are: eu fui, tu foste, ele foi, nós fomos, vós fostes, eles foram.

When do I use the pretérito perfeito instead of the pretérito imperfeito?

Use the pretérito perfeito for one finished action in the past. Use the pretérito imperfeito for an ongoing or habitual past action, or for background description. The time words are your best clue: ontem points to the pretérito perfeito, antigamente points to the pretérito imperfeito.

What are the gerund and past participle of ser?

The gerund is sendo and the past participle is sido. The perfect tenses use ter + sido.

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