Do not interrupt when another is speaking.
Why infinitive form for interrompere here? My first thought was to put imperativo presente for interrompere making it non interrompi . When that did not work , my new grammar book gently assisted me, saying : to ask somebody not to do something, addressing someone with the tu form, use non plus verb infinitive. For all other persons of the imperative, simply add non. Knowing just this one rule, I can correctly answer hundreds of CM questions! Viva il libro di grammatica!