You have to distinguish between indicative and imperative. For verbs in -are they're just swapped, as you noticed, while for -ere and -ire, the 2nd person forms are identical, but you have a difference for the 3rd: (2nd/3rd person) – indicative: (-are) scusi/scusa, (-ere) vedi/vede, (-ire) parti/parte – imperative: (-are) scusa/scusi, (-ere) vedi/veda, (-ire) parti/parta (As Phil said, the 3rd person imperative forms are really subjunctive ones.)

Part 1: It’s the same as in Polish — 3rd person pronouns (pan / pani) are used to mean “you” in formal situations. In Italian, one uses “Lei”, a third person feminine pronoun originally referring to a word of feminine grammatical gender. I’m not sure which word, but something like “grace”, as in “How is your grace today?” Part 2: Since “Lei” is a 3rd person pronoun, there is no imperative form — what’s the imperative for “she”? We can’t tell a 3rd person what to do. Instead we have to use the subjunctive form, as in “qu’ils mangent du gâteau” (“let them eat cake”). Note that Italian (as Romance languages generally) uses the subjunctive for negative commands for all persons (including the 2nd person). So the grammar of “scusi” is “may /let your grace excuse”.

Hi Aria, TU form: Scusa LEI form: Scusi Example: 1. Maria *scusa* per il ritardo (Maria is a friend of mine and I can use Tu Form) 2. Sig.ra mi *scusi* per il ritardo (Misses is not a friend and you can use Lei Form) :) Bye