demostrar Present Conjugation
demostrar — to prove
Demostrar is an o > ue stem-changing verb in all forms except nosotros and vosotros.
demostrar Present Forms
When to Use the Present
Use the present tense to state general facts, show how something works, or express that someone is currently proving a point.
Notes on demostrar in the Present
The 'o' in the stem changes to 'ue' when stressed (demuestro, demuestras, demuestra, demuestran). The nosotros and vosotros forms stay 'o'.
Example Sentences
Yo te demuestro cómo funciona esta máquina.
I'll show (demonstrate to) you how this machine works.
yo
Tú siempre demuestras mucha paciencia.
You always demonstrate a lot of patience.
tú
Nosotros demostramos el proyecto mañana.
We are demonstrating the project tomorrow.
nosotros
Common Mistakes
Mistake: demuostramos
Correct: demostramos
Why: The stem change 'ue' never happens in the nosotros or vosotros forms.
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Related Tenses
Preterite
yo: demostré
Demostrar is regular in the preterite: demostré, demostraste, demostró, demostramos, demostrasteis, demostraron.
Imperfect
yo: demostraba
Demostrar is regular in the imperfect: demostraba, demostrabas, demostraba, demostrábamos, demostrabais, demostraban.
Future
yo: demostraré
The future of demostrar is regular: demostraré, demostrarás, demostrará, demostraremos, demostraréis, demostrarán.
Conditional
yo: demostraría
The conditional of demostrar is regular: demostraría, demostrarías, demostraría, demostraríamos, demostraríais, demostrarían.
Present Subjunctive
yo: demuestre
Demostrar has a stem change (o > ue) in the subjunctive, except for nosotros and vosotros.
Imperfect Subjunctive
yo: demostrara
The imperfect subjunctive is regular: demostrara, demostraras, demostrara, demostráramos, demostrarais, demostraran.
Affirmative Imperative
yo: demuestra
The imperative uses 'demuestra' (tú) and 'demuestre' (usted), following the o > ue stem change.
Negative Imperative
yo: no demuestres
The negative imperative uses the present subjunctive: no demuestres, no demuestre, no demostremos, no demostréis, no demuestren.