A buoy with a composite group-flashing light indicates a(n)（）.

单项选择题A buoy marking a wreck will show a(n)（）.

A.white light FL (2) and a topmark of 2 black spheres
B.occulting green light and may be lettered
C.yellow light and will be numbered
D.continuous quick white light and may be numbered

单项选择题A buoy having red and green horizontal bands would have a light characteristic of（）.

A.interrupted quick flashing
B.composite group flashing
C.Morse (A)
D.quick flashing

单项选择题A bold reef is a reef（）.

A.with part of it extending above the water
B.that can be detected by water turbulence
C.that drops off sharply
D.perpendicular to the current

单项选择题（）means the curve on the earth’s surface which cuts all the meridians at the same angle.

A.Great Circle
B.Position Line
C.Rhumb line
D.True Bearing

单项选择题（）is the process by which the position of the vessel at any moment is found by applying the last well-determined position to the run that has been made since，using for this purpose the ship’s course and the distance being those indicated by log.

A.dead reckoning
B.dead weight
C.dead slow ahead
D.dead slow astern