sustituir Imperfect Subjunctive Conjugation
sustituir — to replace
The imperfect subjunctive is built from the 'sustituyeron' stem: sustituyera, sustituyeras, etc.
sustituir Imperfect Subjunctive Forms
When to Use the Imperfect Subjunctive
Use this for hypothetical 'if' situations (e.g., 'If I replaced...') or past requests involving a substitution.
Notes on sustituir in the Imperfect Subjunctive
Because it is based on the preterite third-person plural, the 'y' is present in every form.
Example Sentences
Si sustituyeras el aceite, el motor funcionaría mejor.
If you replaced the oil, the engine would run better.
tú
Me pidió que sustituyera a María en la reunión.
He asked me to replace Maria in the meeting.
yo
Common Mistakes
Mistake: Using 'sustituiera' instead of 'sustituyera'.
Correct: sustituyera
Why: This tense always derives from the preterite 'ellos' form (sustituyeron), which already contains the 'y'.
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Related Tenses
Present
yo: sustituyo
Sustituir is irregular in the present tense, adding a 'y' before the ending in most forms: sustituyo, sustituyes, sustituye, sustituyen.
Preterite
yo: sustituí
In the preterite, sustituir changes 'i' to 'y' in the third-person forms: sustituyó and sustituyeron.
Imperfect
yo: sustituía
Sustituir is regular in the imperfect: sustituía, sustituías, sustituía, sustituíamos, sustituíais, sustituían.
Future
yo: sustituiré
The future of sustituir is regular: just add endings to the infinitive (sustituiré, sustituirás).
Conditional
yo: sustituiría
The conditional is regular: add -ía endings to the infinitive 'sustituir'.
Present Subjunctive
yo: sustituya
The present subjunctive follows the 'yo' form of the present indicative, adding a 'y': sustituya, sustituyas, etc.
Affirmative Imperative
yo: sustituye
Give commands to replace things: sustituye (tú), sustituya (usted), sustituyamos (nosotros).
Negative Imperative
yo: no sustituyas
Negative commands use the present subjunctive forms: no sustituyas, no sustituya.