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（）.

A.vessel towing astern
B.barge pushed ahead
C.vessel towing astern only when the length of her tow exceeds 200 meters
D.this signal does not exist in international waters

单项选择题You hear the fog signal of another vessel forward of your beam.Risk of collision may exist.You MUST（）.

A.Reduce speed to bare steerageway
B.Stop your engines
C.Begin a radar plot
D.All of the above

单项选择题You are underway in reduced visibility.You hear the fog signal of another vessel about 20° on your starboard bow.Risk of collision may exist.You should（）.

A.alter course to starboard to pass around the other vessel
B.reduce your speed to bare steerageway
C.slow your engines and let the other vessel pass ahead of you
D.alter course to port to pass the other vessel on its portside

单项选择题You are underway and approaching a bend in the channel where vessels approaching from the opposite direction cannot be seen．You should sound（）.

A.one blast，4 to 6 seconds in duration
B.three blasts，4 to 6 seconds in duration
C.one continuous blast until you are able to see around the bend
D.one blast，8 to 10 seconds in duration

单项选择题You are under sail and overtaking a tug and tow.Which action is correct（）.

A.The power-driven tug must maneuver to avoid collision
B.You must maneuver to avoid the tug and tow
C.You must maneuver to avoid collision only if the tug is to leeward and the wind is on your port side
D.Both vessels are required to maneuver to avoid collision