单项选择题
A.red lights
B.red lights and two white lights
C.red lights with a white light in between
D.white lights with a red light in between
单项选择题 As a vessel falls off the wind from close-hauled to a beam reach，the tendency for the vessel to move sideways through the water will（）.
单项选择题 As a ship moves through the water，it drags with it a body of water called the wake. The ratio of the wake speed to the ship’s speed is called（）.
单项选择题 Apparent wind speed blowing across a vessel under tow can be measured by a(n)（）.