prevenir Present Subjunctive Conjugation
prevenir — to prevent
The present subjunctive uses the 'preveng-' stem: prevenga, prevengas, prevenga.
prevenir Present Subjunctive Forms
When to Use the Present Subjunctive
Use this after expressions of desire, doubt, or necessity, such as 'Es importante que...' or 'Dudo que...'.
Notes on prevenir in the Present Subjunctive
The stem is based on the irregular 'yo' form of the present indicative (prevengo), resulting in 'preveng-' for all people.
Example Sentences
Espero que esto prevenga más discusiones.
I hope this prevents more arguments.
él/ella/usted
Es vital que nosotros prevengamos la contaminación.
It is vital that we prevent pollution.
nosotros
Busco un filtro que prevenga las impurezas.
I'm looking for a filter that prevents impurities.
él/ella/usted
Common Mistakes
Mistake: previenga
Correct: prevenga
Why: While the present indicative has a stem change (previene), the subjunctive stem is strictly 'preveng-'.
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Related Tenses
Present
yo: prevengo
Prevenir is a stem-changing verb (e > ie) with a special 'yo' form: prevengo.
Preterite
yo: previne
Prevenir uses an irregular stem 'previn-' in the preterite: previne, previste, previno...
Imperfect
yo: prevenía
Prevenir is completely regular in the imperfect: prevenía, prevenías, prevenía...
Future
yo: prevendré
Prevenir uses the irregular stem 'prevendr-': prevendré, prevendrás, prevendrá.
Conditional
yo: prevendría
Prevenir uses the irregular stem 'prevendr-' plus -ía endings.
Imperfect Subjunctive
yo: previniera
Based on the preterite stem: previniera, previnieras, previniera.
Affirmative Imperative
yo: prevén
The affirmative commands are: prevén (tú), prevenga (usted), prevengamos (nosotros).
Negative Imperative
yo: no prevengas
Negative commands use 'no' + present subjunctive: no prevengas, no prevenga.