Basar Present Tense Conjugation in Spanish

The present tense of basar — “to base” in English — is the form you need for what happens now, for habits and for general truths. This page gives you the full present conjugation table for basar with all six persons, explains exactly how the tense is formed for this verb, shows when to use it with real examples, and finishes with a quiz so you can test yourself. Basar means to base, and it is the transitive verb for founding an opinion, a theory, a decision or a project on something: you base your opinion on the data, you base a theory on experience. It takes en for the foundation, as in basar mi opinión en los datos. Basar is a regular -ar verb, so the notes below explain exactly where it follows the rules and where it breaks them. To see it in a real sentence: Baso mi opinión en los datos.

Present tense conjugation table: basar

Every person of basar in the present tense. The gerund is basando and the past participle is basado.

Present indicative

Person Form
yo baso
tú basas
él/ella/Ud. basa
nosotros/as basamos
vosotros/as basáis
ellos/ellas/Uds. basan

How the present of basar is formed

The present of basar is built from the stem bas- plus the present endings for -ar verbs. Take the infinitive, drop the -ar ending, and add the ending that matches the person. The table below shows the endings, and the full table above shows them attached to the stem.

Person Ending Form
yo -o baso
tú -as basas
él/ella/Ud. -a basa
nosotros/as -amos basamos
vosotros/as -áis basáis
ellos/ellas/Uds. -an basan

For basar there are no surprises in the present: every form is the stem bas- plus the regular ending, so once you know the endings you know the whole tense.

When to use the present tense with basar

Habits and routines

Use the present for things you do regularly.

Yo baso mi opinión en los datos. — I base my opinion on the data.

General facts

Use the present for facts and general truths that do not change.

Él/Ella basa la teoría en la experiencia. — He bases the theory on experience.

What is happening right now

Use the present for what is happening at this moment.

Ahora, Nosotros/as basamos mi decisión en los hechos. — Right now, We base my decision on the facts.

Near-future plans

Use the present for fixed plans in the near future, especially with mañana or la semana que viene.

Mañana, Tú basas el proyecto en un estudio. — Tomorrow, You base the project on a study.

Instructions and timeless statements

Use the present for instructions, rules and statements that are always true.

Él/Ella basa mi opinión en los datos. — He bases my opinion on the data.

The present vs the preterite

The present and the preterite answer different questions: the present says what happens regularly or right now, while the preterite says what happened once and finished. Compare the same idea in both tenses with basar.

  1. Yo baso mi opinión en los datos. — I base my opinion on the data. / Ayer, Yo basé mi opinión en los datos. — Yesterday, I based my opinion on the data.
  2. Yo baso la teoría en la experiencia. — I base the theory on experience. / Ayer, Yo basé la teoría en la experiencia. — Yesterday, I based the theory on experience.
  3. Yo baso mi decisión en los hechos. — I base my decision on the facts. / Ayer, Yo basé mi decisión en los hechos. — Yesterday, I based my decision on the facts.

Example sentences in the present tense

Seven sentences with basar in the present tense only, covering all six persons.

  1. Yo baso mi opinión en los datos. — I base my opinion on the data.
  2. Tú basas la teoría en la experiencia. — You base the theory on experience.
  3. Él/Ella basa mi decisión en los hechos. — He bases my decision on the facts.
  4. Nosotros/as basamos el proyecto en un estudio. — We base the project on a study.
  5. Vosotros/as basáis mi opinión en los datos. — You base my opinion on the data.
  6. Ellos/as basan la teoría en la experiencia. — They base the theory on experience.
  7. Yo baso mi decisión en los hechos. — I base my decision on the facts.

Common mistakes

  1. Wrong: Yo basa mi opinión en los datos. — Right: Yo baso mi opinión en los datos. — The person matters: basa is the él/ella/Ud. form, while the yo form is baso.
  2. Wrong: Ayer, yo baso la teoría en la experiencia. — Right: Ayer, yo basé la teoría en la experiencia. — With ayer, use the preterite (basé), not the present. The present is for habits and for right now.
  3. Wrong: Using basar where basarse belongs. — Right: Basar means to base, while basarse means to be based on something yourself. — Check the meaning before you choose: basar fits Baso mi opinión en los datos.
  4. Wrong: Espero que él basa la teoría en la experiencia. — Right: Espero que él base la teoría en la experiencia. — After espero que, Spanish needs the subjunctive: base, not the present indicative basa.

Quiz: the present tense of basar

Eight questions on the present tense of basar. Choose the right form, then check the answer key below.

  1. Complete the sentence: Yo ___ mi opinión en los datos. (present tense, yo) A. baso B. basas C. basa D. basamos

  2. Complete the sentence: Tú ___ la teoría en la experiencia. (present tense, tú) A. baso B. basa C. basamos D. basas

  3. Complete the sentence: Él/Ella ___ mi decisión en los hechos. (present tense, él/ella/Ud.) A. basas B. basamos C. basa D. baso

  4. Complete the sentence: Nosotros/as ___ el proyecto en un estudio. (present tense, nosotros/as) A. basa B. basamos C. baso D. basas

  5. Complete the sentence: Vosotros/as ___ mi opinión en los datos. (present tense, vosotros/as) A. basáis B. baso C. basas D. basa

  6. Complete the sentence: Ellos/as ___ la teoría en la experiencia. (present tense, ellos/ellas/Uds.) A. baso B. basas C. basa D. basan

  7. Which is the gerund of basar? A. baso B. basé C. basando D. basado

  8. Which is the past participle of basar, used with haber in the perfect tenses? A. basé B. basado C. basando D. baso

Answer key

  1. baso — The yo present form of basar is baso.
  2. basas — The tú present form of basar is basas.
  3. basa — The él/ella/Ud. present form of basar is basa.
  4. basamos — The nosotros/as present form of basar is basamos.
  5. basáis — The vosotros/as present form of basar is basáis.
  6. basan — The ellos/ellas/Uds. present form of basar is basan.
  7. basando — The gerund of basar is basando: estoy basando.
  8. basado — The past participle of basar is basado: he basado, has basado, ha basado.

Frequently asked questions

How is the present tense of basar formed?

Take the infinitive basar, drop the -ar ending to get the stem bas-, then add the present endings: -o, -as, -a, -amos, -áis, -an. The full table is above, with every person. No, the present of basar is fully regular: the stem bas- plus the standard -ar endings gives every form.

When do I use the present tense of basar?

Use the present for habits, facts and what is happening right now. For example: Baso mi opinión en los datos.

What is the difference between the present and the preterite of basar?

The present (baso) and the preterite (basé) answer different questions: the present is for habits and for right now, while the preterite is for one finished action. Compare them in the contrast section above.

How do I practise the present of basar?

Drill the six forms in the table until you can say them without looking, then use the full conjugation of basar to see how the present fits with the other tenses, and the basar examples and quiz page for more sentences. The Spanish Verb Quiz tests the forms under pressure.

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