单项选择题
The purpose of the “set” hand on an aneroid barometer is to（）.
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
单项选择题 The error in the measurement of the altitude of a celestial body，caused by refraction，increases as the（）.
单项选择题 The boom stops on a pedestal crane prevent the boom from（）.
单项选择题 The average height of the surface of the sea for all stages of the tide over a 19 year period is called（）.
