Rule reminder
This exercise tests all major impersonal constructions at B2 level: si impersonale (with agreement rules), ci si (reflexive impersonal), bisogna/occorre/ci vuole/serve, è + adjective + inf/che + subj, and formal impersonals. Pay attention to agreement, register, and mood.
Formal letter ending: 'Certi di una Vostra favorevole risposta, ___ distinti saluti.' Best completion?