In addition to interrogative adjectives, interrogative pronouns, and interrogative prepositions, one other group of words is also used in the formation of questions—the interrogative adverbs come? (how), dove? (where), perché? (why), and quando? (when).

The following interrogative words are the most commonly used to introduce a question:

A che ora? (At what time?)

Come? (How?)

Come mai? (How come? Why [on earth]? Why ever?)

Dove? (Where?)

Perché? (Why?)

Quando? (When?)

Quanto? (How much?)

Two common contractions are com'è? (a contraction of come è? meaning "how is?") and dov'è? (a contraction of dove è? meaning "where is?"). Again, note that in Italian the subject and verb are inverted in interrogative sentences:

A che ora partono i tuoi amici? (At what time are your friends leaving?)

Come sta Luigi? (How is Louis?)

Dove sono i bambini? (Where are the children?)

Dov'è il bambino? (Where is the child?)

Perché fumi tanto? (Why do you smoke so much?)

Quanto fa due più tre? (How much is two plus three?)

The subject and verb are not inverted with come mai:

Come mai Umberto non è qui? (How come Umberto is not here?/Why ever isn't Umberto here?)