sustituir Present Conjugation
sustituir — to replace
Sustituir is irregular in the present tense, adding a 'y' before the ending in most forms: sustituyo, sustituyes, sustituye, sustituyen.
sustituir Present Forms
When to Use the Present
Use the present tense to talk about current replacements, like swapping a broken part or describing a habit of replacing sugar with honey.
Notes on sustituir in the Present
This is a 'y-inserting' verb. For all forms except nosotros and vosotros, you must add a 'y' after the 'u' before adding the ending.
Example Sentences
Yo sustituyo el azúcar por miel en mi café.
I replace sugar with honey in my coffee.
yo
Él sustituye al director durante las vacaciones.
He replaces the director during the holidays.
él/ella/usted
¿Por qué no sustituís las bombillas viejas?
Why don't you all replace the old light bulbs?
vosotros
Common Mistakes
Mistake: Writing 'sustitue' instead of 'sustituye'.
Correct: sustituye
Why: Verbs ending in -uir (where the 'u' is pronounced) require a 'y' to prevent the 'u' and 'e' from blending incorrectly.
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Related Tenses
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.
Imperfect Subjunctive
yo: sustituyera
The imperfect subjunctive is built from the 'sustituyeron' stem: sustituyera, sustituyeras, 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.