单项选择题

A flashing light is a light that（）.

A.flashes at regular intervals at a frequency of 120 flashes or more per minute
B.is yellow in color
C.is visible over an arc of the horizon of not less than 180°nor more than 225°
D.All of the above

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单项选择题

A drawbridge may use visual signals to acknowledge a vessel’s request to open the draw. Which signal indicates that the draw will NOT be opened immediately?（）.

A.A flashing amber light
B.A fixed red light
C.A white flag raised and lowered vertically
D.A flashing white light

单项选择题

A 95-meter vessel aground sounds which fog signal? （）

A.A rapid ringing of a bell for 5 seconds every two minutes
B.A whistle signal of one short，one prolonged，and one short blast
C.A prolonged blast of the whistle at intervals not to exceed one minute
D.A rapid ringing of a bell for 5 seconds，preceded and followed by three separate and distinct strokes on the bell

单项选择题

A 200-meter vessel restricted in her ability to maneuver，at anchor，will sound a fog signal of（）.

A.a 5 second ringing of a bell forward and a 5 second sounding of a gong aft at intervals of 1 minute
B.one prolonged followed by two short blasts every 2 minutes
C.one prolonged followed by three short blasts every minute
D.one prolonged followed by three short blasts every 2 minutes