During an agency style inspection, it was discovered on the spot that four people were playing cards in the office while they were working  When asking for identity alone, the man wearing glasses said: None of us belong to the unit  The young said: At least one person belongs to the unit  The black face said: I don't know anything  The man in the leather jacket said: At least one is not from the unit
After verification, only one of the four told the truth
The young ones are not from the unit, and the ones with glasses are from the unit