单项选择题
A.lights that must be displayed on anchor buoys
B.the display of load line markings
C.minimum horsepower for tugs involved in rig moves
D.lighting of mobile offshore drilling units being towed
单项选择题 The duration of a prolonged blast of the whistle is（）.
单项选择题 Some lights used as aids to marine navigation have a red sector to indicate a danger area. The limits of a colored sector of a light are listed in the Light List in which of the following manners?（）
单项选择题 On entering from seaward，a starboard side daymark will（）.