单项选择题
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
A.horizontal parallax decreases B.observer's height above sea level increases C.humidity of the atmosphere decreases D.altitude of the body decreases
A.being raised too high B.swinging at sea C.overloading when not in use D.being lowered too low