单项选择题
A.You are the stand-on vessel
B.Risk of collision exists
C.A special circumstances situation exists
D.The other vessel is dead in the water
单项选择题 You see a vessel displaying three lights in a vertical line.The highest and lowest lights are red and the middle light is white.She is also showing a white light at the stern，which is lower than the forward light.It could be a（）.
单项选择题 You see a vessel carrying a black diamond which indicates a（）.
单项选择题 You hear the fog signal of another vessel forward of your beam.Risk of collision may exist.You MUST（）.