A yellow buoy may exhibit a(n)（）.

单项选择题A white buoy with an orange rectangle on it displays（）.

A.directions
B.dangers
C.exclusion areas
D.All of the above

单项选择题A white buoy with an open-faced orange diamond on it indicates（）.

A.danger
B.vessels are excluded from the area
C.the buoy is a mooring buoy
D.operating restrictions are in effect

单项选择题A white buoy with a blue band is（）.

A.an isolated danger mark
B.a hydrographic data collection buoy
C.a mooring buoy
D.marking a restricted area

单项选择题A V-shaped ripple with the point of the V pointing upstream in a river may indicate a（）.

A.submerged rock，not dangerous to navigation
B.sunken wreck，not dangerous to navigation
C.towed-under buoy
D.All of the above

单项选择题A vessel is（）when she is not at anchor，made fast to the shore，or aground.

A.underway
B.making way
C.dead in the water
D.a power driven vessel