Charlie said, "I don’t know what Fred is doing".7/20Charlie said, "I don’t know what Fred is doing".He said that he doesn’t know what Fred is doing.He said that he didn’t know what Fred is doing.He said that he doesn’t know what Fred was doing.He said that he didn’t know what Fred was doing.Giải thíchĐáp án đúng: D Dịch: Anh ấy nói rằng anh ấy không biết Fred đang làm gì.