【单选题】
The alarm signal for engine room catching fire is a blast of random bell follow by （）
A、two knock
B、three knocks
C、four knocks
D、five knocks
查看正确答案
A、A.More than six short blasts and one long blast on the whistle B、B.Continuous blast of the ships whistle for a period of not less than 10 seconds supplemented by the same signal on the general alarm C、C.Three short blasts of the whistle supplemented by the same signal on the general alarm D、D.More than six short blasts and one long blast on the whistle supplemented by the same signal on the general alarm
