Learn Hardcore Spanish (Spain): Cierra sesión cuando uses un ordenador público.

Cierra is the affirmative tú imperative of the verb cerrar (to close). For regular -ar verbs, the affirmative tú command uses the 3rd-person singular present indicative form. Since cerrar is stem-changing (e → ie), the present is: yo cierro, tú cierras, él/ella cierra. So the tú command is Cierra.

How do I say this command formally or to more than one person in Spain?

Usted (formal singular): Cierre sesión cuando use un ordenador público.
Vosotros/as (informal plural, Spain): Cerrad sesión cuando uséis un ordenador público.
Ustedes (formal plural in Spain; default plural in Latin America): Cierren sesión cuando usen un ordenador público.

Why is it uses (subjunctive) after cuando, not usas?

Cuando takes the present subjunctive when it refers to a future, unknown, or hypothetical time. Here, cuando uses un ordenador público = “when(ever) you use (in the future/any time you might use).” Hence uses (present subjunctive) instead of usas (present indicative).

Can I ever say cuando usas instead of cuando uses?

Yes. Use cuando + indicative to talk about habitual, known routines:

Cuando usas ordenadores públicos, siempre cierras sesión. (As a general habit.) But with instructions/commands or future-time reference, use the subjunctive:
Cierra sesión cuando uses un ordenador público.

Could I say si usas instead of cuando uses?

You can. It changes the nuance to “if” rather than “when/whenever”:

Cierra sesión si usas un ordenador público. (If you happen to use one…)
Cierra sesión cuando uses un ordenador público. (Whenever you use one / every time you use one.)

Why is it cerrar sesión and not cerrar la sesión?

Cerrar sesión is a fixed expression in tech contexts meaning “to log out,” and it typically omits the article. You might see la in more explicit contexts (e.g., La sesión sigue abierta; ciérrala), but on buttons, instructions, and general usage, it’s usually cerrar sesión.

Is cerrar sesión reflexive? Should it be cerrarse sesión?

No. It’s not reflexive. You say cerrar sesión, not cerrarse sesión. If you replace sesión with a pronoun because it’s been mentioned, you can use a direct object pronoun:

Tu sesión está abierta; ciérrala. (Close it.)

Could I use salir or desconectar instead of cerrar sesión?

Cerrar sesión is the standard, precise term for “log out.”
Salir can appear on some interfaces, but it can be ambiguous (“exit/quit” an app).
Desconectar(se) often means “disconnect (from the internet/server),” not necessarily “log out.” For clarity, stick to cerrar sesión.

Why ordenador and not computadora?

In Spain, the standard word is ordenador. In much of Latin America, people say computadora (or computador in some countries). Because you specified Spanish (Spain), ordenador is the natural choice.

Is ordenador masculine or feminine, and is un correct?

Ordenador is masculine, so it’s un ordenador (not una). The adjective also agrees: un ordenador público.

What’s the accent in sesión for?

Words ending in a vowel, -n, or -s are normally stressed on the penultimate syllable. Since sesión is stressed on the final syllable (se-SIÓN), it needs an accent on the ó to mark that exception.

Why does público have an accent, and how is it different from publico/publicó?

público (noun/adjective: “public”) is stressed on the first syllable (PU-bli-co), so it takes an accent to mark non-standard stress.
publico (no accent) is the verb form “I publish.”
publicó (accent on the final ó) is “he/she/you (usted) published.”

Why does cierra have rr, and what does that mean for pronunciation?

Between vowels, a single r is a light tap sound; rr signals the strong trilled r. The verb is cerrar, so the forms keep the rr: cierro, cierras, cierra. In Spain, ci in cierra is pronounced with the “th” sound: approx. “THYE-rra,” with a trilled r.

How do I pronounce the whole sentence in Spain?

Cierra: “THYE-rra” (θ + y-glide + trilled r)
sesión: “se-SYON” (stress on -sión; s is like English s)
cuando: “KWAN-do”
uses: “OO-ses” (s like English s)
un ordenador: “oon or-deh-na-DOR” (final stress)
público: “POO-bli-ko” (stress on PÚ-)

Can I put the cuando-clause first? Do I need a comma?

Yes, both orders are fine:

Cierra sesión cuando uses un ordenador público.
Cuando uses un ordenador público, cierra sesión. Use a comma when the cuando-clause comes first.

Is there a natural alternative to cuando uses with an infinitive?

Yes, al + infinitive:

Cierra sesión al usar un ordenador público. This is common and neutral in tone. It’s close in meaning to cuando uses.

Where do pronouns go with imperatives?

Affirmative: attach to the end (and add an accent if needed): Ciérrala (Close it).
Negative: put them before the verb: No la cierres (Don’t close it).

Could I use utilizar instead of usar?

Yes. Utilizar is a near-synonym, often a touch more formal:

Cierra sesión cuando utilices un ordenador público.
Cierre sesión cuando utilice un ordenador público.