問題詳情
3.For safety reasons, radios, CD players, and mobile phones are banned on board, and they must remain __________ until the aircraft has landed.
(A) switched on
(B) switch on
(C) switch off
(D) switched off
參考答案
答案：D
難度：困難0.32
統計：A(0),B(12),C(4),D(8),E(0)