单项选择题
A.directions
B.distances
C.locations
D.All of the above
单项选择题 An orange and white buoy marking an area where operating restrictions are in effect will be marked with which symbol? （）
单项选择题 An orange and white buoy marking a danger area will have what symbol on it?（）
单项选择题 An orange and white buoy indicating a vessel-exclusion area will be marked with what symbol? （）