Learn Hardcore Italian: Se ci fosse un fischio d’allarme, apriremmo subito il cancello. - If there were a warning whistle, we would immediately open the gate.

We’re dealing with a hypothetical situation that isn’t happening (or may never happen) in the present/future. Italian uses the imperfetto congiuntivo (the “imperfect subjunctive,” here fosse) in the protasis of a type 2 conditional to express “if there were….”

What role does ci play in this sentence?

Here ci is the impersonal pronoun that goes with essere to mean “there” (as in English “if there were”). You need ci for existence-there constructions; you can’t say Se fosse un fischio… without it.

What kind of conditional sentence is this and how does it correspond to English?

This is a second (or “hypothetical”) conditional in Italian. The pattern is Imperfetto Congiuntivo in the if-clause and Condizionale Presente in the main clause. In English it corresponds to “If there were an alarm whistle, we would open the gate immediately.”

What is the tense and mood of apriremmo, and why is it used here?

Apriremmo is the first-person-plural form of the condizionale presente (present conditional). It expresses the result of the hypothetical: “we would open.” In type 2 conditionals, the main clause uses the present conditional.

Could I omit subito, and what does it add to the sentence?

Yes, you can omit subito and the sentence stays correct, but you lose the idea of immediacy. Subito means “immediately” or “right away,” specifying how quickly the gate would be opened.

Why is allarme contracted to d’allarme instead of writing di allarme?

In Italian, the preposition di contracts before a vowel-initial word to improve euphony. So di allarme becomes d’allarme, just like d’amico or d’ora.

Can I switch the two clauses? For instance, say Apriremmo subito il cancello se ci fosse un fischio d’allarme?

Absolutely. You can place the main clause first. When the if-clause comes second, the comma is optional (and often dropped). The meaning remains exactly the same.