单项选择题
A.check the liferaft's way B.keep the liferaft end on to the sea C.reduce the possibility of capsizing or broaching D.right the raft if it inflates inverted
A.mean sea level B.mean high water C.mean low water D.half-tide level
A.adjust the barometer B.indicate any change in the reading of the barometer C.provide a correction for height above sea level D.provide a correction for temperature changes