单项选择题
A buoy with a composite group-flashing light indicates a(n)（）.
A.anchorage area B.fish net area C.bifurcation D.dredging area
单项选择题 A buoy marking a wreck will show a(n)（）.
单项选择题 A buoy having red and green horizontal bands would have a light characteristic of（）.
单项选择题 A bold reef is a reef（）.
