单项选择题
An authorized light to assist in the identification of submarines operating on the surface is a(n)（）.
A.blue rotating light B.intermittent flashing amber/yellow light C.flashing white light D.flashing sidelight
单项选择题 An aneroid barometer on a boat should always be（）.
单项选择题 An anchored vessel is servicing an aid to navigation and is restricted in her ability to maneuver. Which lights will she show? （）
单项选择题 An all-round flashing yellow light may be exhibited by a(n)（）.
