Day-shapes must be displayed（）.……

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（）.

A.red lights
B.red lights and two white lights
C.red lights with a white light in between
D.white lights with a red light in between

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（）.

A.will be coming to periscope depth
B.will be coming to the surface
C.is on the bottom in distress
D.is in distress and will try to surface

单项选择题A vessel，which does not normally engage in towing operations，is towing a vessel in distress.She（）.

A.need not show the lights for a vessel engaged in towing，if it is impractical to do so
B.may show the lights for a vessel not under command
C.must show a yellow light above the stern light
D.must show the lights for a vessel towing

单项选择题A vessel sounding a fog signal of one short，one prolonged，and one short blast is indicating that the vessel is（）.

A.fishing
B.in distress
C.at anchor
D.not under command

单项选择题A vessel showing a yellow light over a white light at night is a vessel（）.

A.engaged in piloting
B.towing astern
C.engaged in fishing
D.in distress