Hi, Grammatically speaking: The room must be entered silently. The room is to be entered silently. I don't think they are natural, though.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
AnonymousEnter the room silentlyThere are no passive voice versions of imperatives. If you want something facetious, try "Room, be entered silently!" or "Be entered silently, O Room!"