During an office style inspection, four people were found playing cards in the office during work. When asked individually for identity, those who wore glasses said: "None of us are from the unit. " "The black-faced said:" I don't know anything. "The person wearing a leather jacket said:" At least one of them is not the unit. "It was verified that only one of the four-spoke the truth. This shows:. ["It's not the unit who wears glasses and a leather jacket.", 'The black-faced is the unit, but the young are not the unit.', 'The young are not the unit, and the glasses are the unit.', 'Young and those in leather jackets are from the unit.']