19. 翻譯：遇險中繼信號已被確認。
(A) The DISTRESS-RELAY alert was transmitted.
(B) The DISTRESS-RELAY alert was confirmed.
(C) The DISTRESS-RELAY alert was acknowledgement.
(D) The DISTRESS-RELAY alert was received.

答案：登入後查看
統計： A(0), B(3), C(6), D(3), E(0) #1242878