Section 18.1 · vowel swap rule: start with yo form, drop -o, add opposite vowel · -AR verbs: -e / -en · -ER/-IR verbs: -a / -an · irregular yo forms carry into the command · negatives: add no before the command
In a professional or medical environment, giving clear instructions is a daily necessity. Whether you are asking a patient to sit down, a client to sign a document, or a colleague to wait a moment, you must use the formal command — called the Imperative in Spanish grammar. In the Americas, using the Usted and Ustedes forms shows respect and maintains the professional register expected in formal settings.
Section 18.1 introduces the core mechanism for forming formal commands: the vowel swap rule. Starting from the yo form of the present tense, you drop the final -o and add the “opposite” vowel ending. This rule is regular, predictable, and applies consistently — including carrying over any irregularity already present in the yo form, which means that learning the yo form unlocks the command automatically.
vowel swap rule-AR → -e / -en-ER/-IR → -a / -anyo form carries irregularityno + command = negativetú command = present 3rd sg. / no + usted form
⚡ The Vowel Swap Engine — How to Form Every Formal Command
Start Here
hablar
any infinitive
Step 1 → get the yo form hablo → drop the -o → habl-
⟶
The Commands
Usted (sg.)
Hable
habl + e
Ustedes (pl.)
Hablen
habl + en
▶ -AR Verbs → Add E / EN
Hablar: yo hablo → Hable / Hablen
Firmar: yo firmo → Firme el doc. / Firmen aquí
Caminar: yo camino → Camine / Caminen
Esperar: yo espero → Espere / Esperen
▶ -ER / -IR Verbs → Add A / AN
Comer: yo como → Coma / Coman
Escribir: yo escribo → Escriba / Escriban
Beber: yo bebo → Beba / Beban
Abrir: yo abro → Abra / Abran
The “opposite vowel” trick: -AR verbs normally use -a endings in the present tense (habla, hablan) — but in Usted/Ustedes commands they use the opposite: -e / -en. -ER/-IR verbs normally use -e endings — but in commands they use -a / -an. The vowel swap is exactly that: swapping to the vowel the verb doesn’t normally use. Note on Tú commands: The informal Tú affirmative command is simply the present-tense él/ella form — habla, come, escribe — no vowel swap needed. Only Usted/Ustedes commands use the vowel swap.
⚡ Verbs with Irregular Yo Forms — The Irregularity Carries Over
hacer
hago
Haga
Hagan
tener
tengo
Tenga
Tengan
decir
digo
Diga
Digan
poner
pongo
Ponga
Pongan
venir
vengo
Venga
Vengan
Why irregular yo forms matter for commands: Because the vowel swap starts from the yo form, any irregularity in yo carries directly into the command. Hacer → hago → hag- + a = haga. Tener → tengo → teng- + a = tenga. This means you do not need to memorize irregular commands separately — memorizing the irregular yo forms (hago, tengo, digo, pongo, vengo, salgo, traigo...) is sufficient to produce any command from those verbs.
🚫 Negative Commands — Simply Add No Before the Command
✓ Affirmative Command
Hable ahora. Firme el contrato. Coman en la sala. Abran las ventanas. Tenga cuidado.
✗ Negative Command
No hable ahora. No firme el contrato todavía. No coman en la oficina. No abran la caja. No tenga miedo.
The command form does not change for negatives. The same command ending is used for both affirmative and negative Usted/Ustedes commands. Only the addition of no before the verb changes the meaning. Key contrast with Tú commands: Informal tú negative commands use the same form as the Usted command — No hables, no comas, no escribas — while the tú affirmative command is different: habla, come, escribe. So: Hable / No hable (Usted) vs. Habla / No hables (tú). The formal Usted form is simpler because affirmative and negative share the same ending.
▶ Tú vs. Usted Commands — Two “You” Forms, Two Different Rules
Tú — Informal Affirmative
Hablar → Habla (present tense 3rd sg.)
Comer → Come
Escribir → Escribe
Hacer → Haz (irregular)
Tener → Ten (irregular)
Usted — Formal Affirmative
Hablar → Hable (vowel swap: -e)
Comer → Coma (vowel swap: -a)
Escribir → Escriba (vowel swap: -a)
Hacer → Haga (irregular yo + -a)
Tener → Tenga (irregular yo + -a)
Tú — Informal Negative
No hables (= no + Usted form + -s) No comas No escribas No hagas No tengas
Usted — Formal Negative
No hable No coma No escriba No haga No tenga
The key pattern: Tú affirmative commands = present-tense él/ella form (habla, come, escribe) — no vowel swap. Usted commands always use the vowel swap from the yo form. For negatives, both tú and Usted use the same vowel-swapped form — the only difference is that tú negative adds -s: No hable (Usted) vs. No hables (tú). In the Americas, Usted is the default in professional settings; tú is for friends, family, and informal contexts.
📊 Vocabulary Chart: Common Professional Commands
Spanish Command
Tú Form
Usted Form
Audio
Pase / Pasa
Pasa (tú)
Pase (usted) — Come in / Go ahead
Siéntate / Siéntese
Siéntate (tú)
Siéntese (usted) — Sit down
Díme / Dígame
Díme (tú)
Dígame (usted) — Tell me / Go ahead
Espera / Espere
Espera (tú)
Espere (usted) — Wait / Hold on
Firma / Firme aquí
Firma aquí (tú)
Firme aquí (usted) — Sign here
1. The Vowel Swap Rule — From Yo Form to Command
yo form → drop -o → add opposite vowel · -AR → -e/-en · -ER/-IR → -a/-an
Formal commands (Usted/Ustedes) are formed by starting with the first-person singular (yo) present tense form, dropping the final -o, and adding the “opposite” vowel ending. For -AR verbs: drop -o, add -e (singular) or -en (plural). For -ER and -IR verbs: drop -o, add -a (singular) or -an (plural). The vowel is “opposite” because -AR verbs normally end in -a but the command uses -e, and -ER/-IR verbs normally end in -e but the command uses -a. The yo form is the key: hablar → hablo → habl- → hable/hablen. Comer → como → com- → coma/coman.
The stem is everything: Dropping -o from the yo form gives the command stem. Any change that affects the yo form — stem changes, spelling changes, irregular formations — automatically appears in the command stem. If you know the yo form, you can build any formal Usted command mechanically. There is no separate set of command stems to memorize. Tú contrast: The informal tú affirmative command does not use the vowel swap — it simply uses the present-tense third-person singular form: habla, come, escribe. The vowel swap is a feature of formal Usted commands only.
✏️ The vowel swap in action across verb types:
Hablar: hablo → Hable despacio, por favor.
Firmar: firmo → Firme el documento aquí.
Comer: como → Coma bien antes de la cirugía.
Escribir: escribo → Escriba su nombre completo aquí.
Abrir: abro → Abra la puerta principal, por favor.
2. Plural Commands — Ustedes with -en / -an
hablen · firmen · coman · escriban · addressing a group · same vowel swap, add -n
When addressing a group (Ustedes), the same vowel swap applies but with an added -n: -en for -AR verbs and -an for -ER/-IR verbs. Hablen en voz alta (Speak up). Firmen los papeles (Sign the documents). Coman ahora (Eat now). Escriban el reporte (Write the report). In professional or medical environments, the plural command is essential when addressing a waiting room, a team, or multiple clients simultaneously. The logic is identical to the singular — the only difference is the additional -n that makes it plural. A helpful way to remember: singular = drop -o + opposite vowel; plural = drop -o + opposite vowel + n.
In the Americas, Ustedes is the only plural “you”: In Spain, vosotros is used for informal plural. In the Americas (Mexico, Central America, South America), Ustedes serves as the plural form for all contexts — both formal and informal. This means Ustedes commands are the only plural commands you need in American Spanish, making the system simpler than it appears in Spanish textbooks written for Spain.
✏️ Ustedes plural commands in professional context:
Hablen con el doctor antes de salir del hospital.
Firmen los papeles en el mostrador de recepción.
Esperen en la sala hasta que los llamen.
Coman a las doce — el comedor está en el segundo piso.
Escriban su nombre y número en la hoja de asistencia.
3. Irregular Yo Forms — The Irregularity Stays in the Command
Many high-frequency verbs have irregular yo forms: hacer → hago, tener → tengo, decir → digo, poner → pongo, venir → vengo, salir → salgo, traer → traigo, conocer → conozco. Because the vowel swap starts from the yo form, these irregularities automatically carry into the command. Hago → hag- → haga/hagan. Tengo → teng- → tenga/tengan. Digo → dig- → diga/digan. Pongo → pong- → ponga/pongan. Vengo → veng- → venga/vengan. This is one of the most useful features of the vowel swap rule: a single rule covers both regular and irregular verbs, as long as you know the yo form.
Tenga cuidado and Hagan las cosas bien — two fixed expressions:Tenga cuidado (Be careful / Take care) and Hagan las cosas bien (Do things right) are extremely high-frequency professional expressions. Dígame (Tell me) and Ponga su firma (Put your signature) are essential in medical and office settings. Mastering these five verbs (hacer, tener, decir, poner, venir) in their command forms covers a large portion of the commands you will use daily.
✏️ Irregular yo commands in professional use:
Haga el trabajo antes de las tres de la tarde.
Tenga cuidado — el piso está mojado.
Diga la verdad — es importante para el expediente.
Ponga su firma en la línea de abajo, por favor.
Vengan a la oficina el lunes a las nueve de la mañana.
4. Negative Commands — No Before the Command Form
no hable · no firme · no coman · no abran · command form unchanged · no = don’t
Forming a negative formal command is the simplest transformation in Spanish: place no directly before the command verb. The command form itself does not change at all. Hable → No hable ahora. Firme → No firme el contrato todavía. Coman → No coman en la oficina. Abran → No abran la caja. Tenga → No tenga miedo. The same ending that produces the affirmative command produces the negative command — the only addition is no at the start. This consistency makes formal negative commands much easier than informal (tú) negative commands, which use a completely different verb form.
Affirmative vs. negative command comparison — same ending for Usted, different for Tú: For Usted: Hablar → Hable (speak) / No hable (don’t speak). Comer → Coma (eat) / No coma (don’t eat). The ending is identical. For Tú (informal): Hablar → Habla (speak, affirmative) / No hables (don’t speak, negative). Comer → Come (eat, affirmative) / No comas (don’t eat, negative). Notice that the negative tú command (no hables, no comas) uses the formal Usted command stem plus -s — a completely different form from the affirmative. This is why knowing both systems is essential.
✏️ Negative commands in professional context:
No hable durante el procedimiento, por favor.
No firme el contrato todavía — revíselo primero.
No coman nada después de la medianoche antes de la operación.
No abran la caja hasta que llegue el supervisor.
No tenga miedo — el procedimiento es rápido y sin dolor.
5. Professional Command Phrases — Pase, Siéntese, Dígame
pase · siéntese · dígame · espere · firme aquí · essential five for any workplace
Five command phrases are used so frequently in professional and medical settings that they function as essential building blocks of workplace Spanish. Pase (Come in / Go ahead — from pasar): used to welcome someone into a room or invite them forward. Siéntese (Sit down — from sentarse, reflexive): the pronoun se is attached to the command. Dígame (Tell me / Go ahead — from decir + me): irregular yo form digo → dig- → diga, but with the pronoun me attached = dígame. Espere (Wait / Hold on): standard -AR command. Firme aquí (Sign here): essential for any transaction. These five phrases alone cover a large percentage of daily professional command use.
Siéntese and Dígame — commands with attached pronouns: Both of these vocabulary words have pronouns attached to the end of the command: siéntese (sit yourself down, from sentarse) and dígame (tell me). This is a preview of Section 18.4, which covers attaching object pronouns to affirmative commands. For now, treat these two as fixed phrases to memorize. Note that attaching the pronoun requires a written accent to maintain the stress: díga + me = dígame, sienté + se = siéntese.
✏️ The five essential professional commands:
Pase, por favor — el doctor lo espera en el consultorio.
Siéntese aquí — le atendemos en unos minutos.
Dígame, ¿en qué le puedo ayudar hoy?
Espere un momento — voy a revisar su expediente.
Firme aquí, por favor — y feche con la fecha de hoy.
6. Informal Tú Commands — How They Differ from Usted
habla · come · escribe · tú affirmative = 3rd person sg. · tú negative = formal stem + s
While this section focuses on formal Usted/Ustedes commands, you will constantly encounter and need to use the informal tú command in everyday life — with friends, family, children, and colleagues you are on familiar terms with. The tú command follows a completely different pattern from the formal system. Affirmative tú commands use the third-person singular present tense (the él/ella form): habla, come, escribe, abre, tiene, hace. There is no vowel swap. Negative tú commands, however, use the formal Usted command form plus -s: no hables, no comas, no escribas, no abras. This asymmetry — affirmative from one system, negative from another — is the most important feature of the tú command to master.
Side-by-side comparison — Usted vs. Tú:
Hablar (to speak):
Usted affirmative: Hable · Usted negative: No hable
Tú affirmative: Habla · Tú negative: No hables
Comer (to eat):
Usted affirmative: Coma · Usted negative: No coma
Tú affirmative: Come · Tú negative: No comas
Escribir (to write):
Usted affirmative: Escriba · Usted negative: No escriba
Tú affirmative: Escribe · Tú negative: No escribas
Key pattern: the negative tú command (no hables) looks like the formal Usted command (hable) + s. Knowing the Usted command unlocks the negative tú command automatically.
✏️ Tú commands — affirmative and negative in everyday context:
Habla más despacio, por favor — no te entiendo.
No hables tan rápido — necesito escucharte bien.
Come algo antes de salir — el desayuno es importante.
No comas en el cuarto — usa la cocina, por favor.
Escribe tu nombre aquí y firma abajo.
No escribas con lápiz — usa bolígrafo para el formulario.
📌 Key Rules — Usted and Ustedes Commands at a Glance
The vowel swap rule (Usted/Ustedes): Start with the yo form → drop -o → add opposite vowel. -AR verbs: add -e (sg.) / -en (pl.). -ER/-IR verbs: add -a (sg.) / -an (pl.).
Irregular yo forms carry over: hago → haga/hagan · tengo → tenga/tengan · digo → diga/digan · pongo → ponga/pongan · vengo → venga/vengan. No separate memorization needed — know the yo form, know the command.
Negative Usted/Ustedes commands: Add no before the command form. The command ending does not change. No hable · no firme · no coman · no abran · no tenga.
Tú commands — affirmative: Use the third-person singular present tense (the él/ella form). Habla · come · escribe · abre. No vowel swap. No -o drop. Simply the 3rd-person singular form.
Tú commands — negative: Use the formal Usted command stem + s. No hables · no comas · no escribas · no abras. The negative tú command and the formal Usted command share the same stem — only the -s distinguishes them.
The key contrast: Usted affirmative and negative use the same ending. Tú affirmative and negative use different forms. Mixing these up is one of the most common errors for English speakers.
Essential professional phrases: Pase · Siéntese · Dígame · Espere · Firme aquí. Memorize these five as complete fixed expressions for immediate use.
Ustedes in the Americas: Ustedes commands (-en / -an) serve all plural formal and informal contexts in American Spanish. No vosotros commands needed.
Preview — Sections 18.2–18.4: 18.2 expands affirmative and negative commands · 18.3 covers fully irregular commands (ser → sea, ir → vaya, saber → sepa, dar → dé) · 18.4 covers attaching object pronouns to affirmative commands (fírmelo, dígame, tráigala).
Shadow & Speak — Section 18.1-A
Listen to each command, then repeat aloud during the countdown.
Sentences 1–5 drill the vowel swap for -AR verbs (hable, firme, camine, espere, pase) in realistic professional contexts. Sentences 6–10 drill -ER/-IR verbs (coma, escriba, beba, abra, reciba) to build contrast with the opposite vowel. Sentences 11–15 drill Ustedes plural commands (-en/-an) for both verb types in group instruction settings. Sentences 16–20 drill irregular yo commands (haga, tenga, diga, ponga, venga) with full professional sentences. Sentences 21–25 drill negative commands (no hable, no firme, no coman, no abran, no tenga) alongside their affirmative equivalents. Sentences 26–31 drill informal Tú commands — both affirmative (3rd-person singular form) and negative (formal stem + s) — contrasting the two systems directly.
How to Shadow & Speak
Step 1 — Label the type before speaking: For each command, mentally label: verb type (-AR or -ER/-IR), number (Usted sg. or Ustedes pl.), and whether it is regular or irregular yo. This active labeling converts passive imitation into genuine grammatical production.
Step 2 — Produce the yo form first, silently: Before speaking the command aloud, flash the yo form through your mind: hablar → hablo → hable. This builds the mechanical pathway from verb to command and prevents memorizing commands as disconnected vocabulary.
Step 3 — Contrast pairs: After each negative command (sentences 21–25), immediately produce the affirmative equivalent. After No hable, say Hable. This pairing locks both forms into active use simultaneously.
Study Tips
The yo-form flashcard drill: For each verb in this section, make a chain: infinitive → yo form → usted command → ustedes command. Example: hacer → hago → haga → hagan. Drill until the chain runs without hesitation. Seven chains: hablar, firmar, comer, escribir, hacer, tener, decir.
Professional command simulation: Choose a scenario (receptionist greeting patients / supervisor giving instructions / doctor explaining a procedure) and generate five commands appropriate to that context. Use both affirmative and negative. Example scenarios: welcoming a patient, directing a signing, explaining a medical procedure, addressing a group before a meeting.
Anchor the five essential phrases: Commit Pase · Siéntese · Dígame · Espere · Firme aquí to immediate recall. Write them on a card, post it at your workstation, and use one in every Spanish interaction this week. Frequency exposure with real context is the fastest path to automatic production.
Progress: 0 / 31
Speed1.0
Volume1.0
Press START to begin
Presiona INICIO para comenzar
Quiz — Section 18.1-B
Choose the correct answer. 20 questions drawn randomly from a pool of 30.