12. 夜晚使用岸上救生器材時，表示已掌握火箭索之聯絡信號，使用白燈一盞或手持白焰作何種動作？ (A)上下擺動 (B)左右擺動 (C) 繞圈運動 (D) 高舉不動

17. Your vessel was vibrated heavily at a range of numbers of revolutions of the engines because synchronization occurs between the periods of a vibration of the hull and those caused by the inertia of the reciprocating parts of engines. What do we call this speed? (A)Regulative speed. (B)Critical speed. (C)Calibrating speed. (D)Difficult speed.