Learn Hardcore Spanish (Spain): Antes de que lleguen mis padres, debería preparar la mesa para que todo esté listo. - Before my parents arrive, I should set the table so that everything is ready.

Because antes de que introduces a time clause referring to a future, not-yet-realized event. In Spanish, time clauses about future events often require the present subjunctive: antes de que lleguen. Using the indicative (llegan/llegarán) here would be incorrect.

Why is it antes de que, not antes que or just antes de?

With a finite verb clause, standard Spanish uses antes de que: antes de que lleguen.
Antes que is used mainly in comparisons (e.g., antes que tú) or in certain set expressions, not here.
Antes de alone is followed by an infinitive when the subject is the same: Antes de llegar, debería…

Could I say Antes de llegar, instead of antes de que lleguen?

Only if the subject is the same in both actions (you). For different subjects (they arrive / I prepare), Spanish prefers a finite clause: antes de que lleguen mis padres. So:

Same subject: Antes de llegar, debería preparar la mesa.
Different subjects: Antes de que lleguen mis padres, debería…

Why is esté (subjunctive) used after para que?

Para que expresses purpose and takes the subjunctive. You’re stating the goal: “so that everything be ready.” If the subject were the same, you’d use para + infinitive: para tener todo listo.

What’s the nuance of debería vs debo vs tengo que?

Debería: mild/soft suggestion (“I should”), polite and less forceful.
Debo: stronger sense of duty (“I must/ought to”), a bit formal.
Tengo que: everyday, clear necessity (“I have to”), often stronger than debería.

Is debería de correct here?

Prefer debería (without de) for obligation. In Spain, deber de is typically used for probability/assumption (e.g., debe de ser tarde = “it must be late”). For “should prepare,” use debería preparar.

Can I switch the word order to antes de que mis padres lleguen?

Yes. Both antes de que lleguen mis padres and antes de que mis padres lleguen are correct. Spanish allows subject–verb flexibility, especially in subordinate clauses.

Why is there a comma after the first clause?

When a subordinate clause comes first, Spanish normally uses a comma before the main clause: Antes de que…, (comma) debería… If the main clause comes first, you usually don’t add a comma before the connector: Debería preparar la mesa antes de que lleguen…

Why not use a future tense like llegarán?

In subordinate time clauses (with cuando, en cuanto, antes de que, etc.) that refer to the future, Spanish uses the present subjunctive rather than the future indicative. Hence, lleguen, not llegarán.

What’s the difference between esté and está here?

Purpose clauses with para que require the subjunctive, so esté is mandatory. Para que todo esté listo = “so that everything is ready.” Using está would be ungrammatical in this structure.

Why does listo appear in masculine singular with todo?

Todo here is an indefinite pronoun meaning “everything,” and adjectives agree with it in masculine singular by default: todo esté listo. This is standard: masculine singular is the default agreement for “everything.”

Is preparar la mesa the most natural in Spain?

You’ll certainly be understood, but in Spain the idiomatic expression is poner la mesa (“to set the table”). A very natural sentence would be: Antes de que lleguen mis padres, debería poner la mesa para que todo esté listo.

Can I say para que esté todo listo instead of para que todo esté listo?

Yes. Both orders are correct and common. Spanish often allows subject–verb inversion in subordinate clauses: para que todo esté listo / para que esté todo listo.

Is de que here an example of the error called “dequeísmo”?

No. Antes de que is the standard, required form with this conjunction. The de belongs to antes de, so it’s not an extraneous de.

Could I use the present perfect subjunctive, as in antes de que hayan llegado mis padres?

It’s unusual here. Antes de que lleguen mis padres is the normal way to talk about a future arrival. You’d use perfect subjunctive with expressions like para cuando: Para cuando hayan llegado mis padres, todo debería estar listo.

Why no yo before debería?

Spanish commonly drops subject pronouns because the verb ending shows the subject. Debería already implies yo. You can add yo for emphasis: Yo debería preparar la mesa…

Why estar listo and not ser listo?

With listo, estar means “to be ready,” a temporary state. Ser listo means “to be clever,” a permanent trait. Here the meaning is “ready,” so estar is correct.