单项选择题
A yellow buoy may exhibit a(n)（）.
A.fixed red light B.flashing light C.white light D.occulting light
单项选择题 A white buoy with an orange rectangle on it displays（）.
单项选择题 A white buoy with an open-faced orange diamond on it indicates（）.
单项选择题 A white buoy with a blue band is（）.
