单项选择题
A.horizontal parallax decreases B.observer's height above sea level increases C.humidity of the atmosphere decreases D.altitude of the body decreases
The boom stops on a pedestal crane prevent the boom fro...
单项选择题The boom stops on a pedestal crane prevent the boom from（）.
A.being raised too high B.swinging at sea C.overloading when not in use D.being lowered too low
The average height of the surface of the sea for all st...
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（）.
A.mean high water B.mean low water C.half-tide level D.mean sea level
The 3-cm radar as compared to a 10-cm radar with simila...
单项选择题The 3-cm radar as compared to a 10-cm radar with similar specifications will（）.
A.give better range performance in rain，hail，etc B.display small targets in a mass of dense sea clutter at a greater range C.have less sea return in choppy rough seas D.display a more maplike presentation for inshore navigation
