单项选择题 Public address system: loudspeakers in the vessel’s cabins, mess rooms, ETC., and on deck via which important information can bebroadcast from a central point, mostly from the navigation bridge defines（）.

单项选择题 The speed at which a storm centre moves is the（）.

单项选择题 The speed of a vessel adjusted to that of a pilot boat at which the pilot can safely embark is（）.