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? （）
单项选择题 A 200-meter vessel restricted in her ability to maneuver，at anchor，will sound a fog signal of（）.
单项选择题 A 200-meter vessel is aground in fog. Which signal is optional? （）
