(A) Hardly he had arrived (B) at the airport when he (C) realized that
Giải thích
Chọn đáp án A(Hardly he had Hardly had he)
Cấu trúc: Hardly + had + S + pp... + when + S + V-past...
"Anh ấy vừa mới đến sân bay thì anh ấy nhận ra rằng anh ấy đã quên ví."