DEAR MISS MANNERS: I frequently see people going about their business whose masks have slipped below the nose. And I don’t want to get into one of those explosive confrontations between people who are for or against wearing masks. These people are wearing masks, it’s just that they’re not wearing them effectively. Miss Manners has wandered into this quaint tangent in search of a quick hint that can be quietly conveyed to someone whose mask has slipped. So a quiet “Excuse me, I believe your mask has slipped,” accompanied by a sympathetic smile, will have to do.