Every vessel shall（）maintain a proper look-out by sight and hearing as well as by all available means appropriate in prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.

单项选择题During the day，a vessel picking up a submarine cable shall carry（）.

A.Three shapes，the highest and lowest shall be red balls，and the middle shall be a white diamond
B.Two black balls
C.Three shapes；the highest and lowest shall be black balls，and the middle shall be a red diamond
D.Three shapes；the highest and lowest shall be black balls and the middle shall be a black diamond

单项选择题Dring a period of “whiteout”，you should expect which of the following（）.

A.Snowfall or blowing snow
B.Lack of ability to estimate distance
C.Harsh contrast between sun-illuminated snow cover and the background
D.Hazy horizons with extensive mirage effects

单项选择题Day-shapes must be displayed（）.

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（）.

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