Breakdown of È necessario che l'allarme funzioni bene.
essere
to be
bene
well
che
that (conjunction introducing a clause)
funzionare
to work / to function (machines, devices)
Questions & Answers about È necessario che l'allarme funzioni bene.
Why is funzioni used here instead of funziona?
The phrase è necessario che (it is necessary that) is an impersonal expression that shows necessity. In Italian, these expressions always trigger the subjunctive mood in the following verb. Because funzionare is an -are verb, its he/she/it form in the present subjunctive ends in -i, making it funzioni.
Do all phrases starting with 'È + adjective + che' trigger the subjunctive?
Most do, especially when they express opinion, necessity, emotion, or doubt, like è importante che or è probabile che. However, if the expression states an absolute certainty or a clear fact, like è certo che (it is certain that) or è vero che (it is true that), you use the normal indicative mood instead.
Don't the io and tu forms of -are verbs in the subjunctive also end in -i? How do we know who is doing the action?
Yes, in the present subjunctive, the io, tu, and lui/lei forms are all exactly the same! For funzionare, they are all funzioni. Usually, the subject is obvious from the context, just as l'allarme clarifies it here. If it is ever ambiguous, you simply add the subject pronoun before the verb to make it clear.
Why do we use bene here instead of buono?