Learn Italian: Immaginiamo che il ladro si arrabbi facilmente. - We imagine that the thief gets angry easily.

The main verb immaginare (to imagine) expresses a personal thought or belief. When verbs of thinking, believing, or imagining are followed by che (that), they trigger the subjunctive mood in the dependent clause because the action is viewed as subjective rather than a stated fact.

How does the reflexive verb arrabbiarsi work in the subjunctive here?

It works just like it does in the regular present tense. The reflexive pronoun si goes right before the verb. Because arrabbiarsi is a regular -are verb, its third-person singular present subjunctive ending is -i, resulting in si arrabbi.

Wait, doesn't arrabbi look like the tu (you) form in the normal present tense?

Yes, it does! That can be tricky for learners. For regular -are verbs, the present subjunctive endings for io, tu, and lui/lei are all identical: they all end in -i. Here, il ladro (he) is the subject, so we know we are looking at the lui/lei subjunctive form.

How do we get the adverb facilmente?