单项选择题
A.lower ballast tanks are filled with water
B.sea anchor is deployed to windward
C.fuel tanks are not less than half full
D.passengers are strapped to their seats
单项选择题 Mean low water is the average height of（）.
单项选择题 In the Sargasso Sea there are large quantities of seaweed and no well defined currents. This area is located in the（）.
单项选择题 In the Northern Hemisphere you are caught in the dangerous semicircle of a storm with plenty of sea room available. The best course of action is to bring the wind on the（）.