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? （）
A.Open-faced diamond B.Diamond with a cross C.Circle D.Rectangle
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? （）
单项选择题 A yellow buoy may mark a(n)（）.
