prevenir Preterite Conjugation
prevenir — to prevent
Prevenir uses an irregular stem 'previn-' in the preterite: previne, previste, previno...
prevenir Preterite Forms
When to Use the Preterite
Use the preterite to describe a specific moment in the past when someone took action to stop something from happening.
Notes on prevenir in the Preterite
This is a highly irregular 'u-stem' verb (though it looks like 'i'). The stem changes to 'previn-' and uses the irregular preterite endings (no accents).
Example Sentences
El médico previno la enfermedad a tiempo.
The doctor prevented the illness in time.
él/ella/usted
Previne el error revisando el informe dos veces.
I prevented the error by checking the report twice.
yo
Ellos previnieron un desastre mayor.
They prevented a major disaster.
ellos/ellas/ustedes
Common Mistakes
Mistake: prevení
Correct: previne
Why: Prevenir uses the irregular stem 'previn-' in the preterite, not the regular -ir endings.
Mistake: previnio
Correct: previno
Why: The third-person singular of irregular preterite verbs ends in -o, not -ió.
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Related Tenses
Present
yo: prevengo
Prevenir is a stem-changing verb (e > ie) with a special 'yo' form: prevengo.
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.
Present Subjunctive
yo: prevenga
The present subjunctive uses the 'preveng-' stem: prevenga, prevengas, prevenga.
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.