WHY WAS PAUL CORNU'S FLIGHT IMPORTANT

55. - File thứ 1: De va dap an thi thu lan 2, Anh
Tiếng Anh File thứ 1: De va dap an thi thu lan 2, Anh
55. Why was Paul Cornu's flight important? A. It was the first practical helicopter flight. B. It was the first time a helicopter lifted into the air without ground assistance. C. It was the first time a helicopter lifted into the air. D. It lasted 7 minutes and 40 seconds.