单项选择题
A.Between sunset and sunrise
B.Only between 8 AM and 4 PM
C.During daylight hours in any visibility
D.During daylight hours in unrestricted visibility only
单项选择题 At night，a vessel shall indicate that she is restricted in her ability to maneuver by showing in a vertical line two（）.
单项选择题 A yellow signal，floating in the air from a parachute，about 300 feet above the water，indicates that a submarine（）.
单项选择题 A vessel，which does not normally engage in towing operations，is towing a vessel in distress.She（）.