单项选择题
A.Red buoy with a horizontal yellow band
B.Red and white vertically-striped buoy with a vertical yellow stripe
C.Red and white vertically-striped buoy with a red spherical topmark
D.Green buoy with a yellow square
单项选择题 What describes an accurate position that is NOT based on any prior position? （）
单项选择题 Uncharted lights，fog signals and radar beacon transmissions may be（）near the station.
单项选择题 Two navigational hazards are located near to each other，but each is marked by an individual cardinal buoyage system. The buoys of one cardinal system may be identified from the other system by（）.