The error in the measurement of the altitude of a celestial body，caused by refraction，increases as the（）.

A.being raised too high
B.swinging at sea
C.overloading when not in use
D.being lowered too low

A.mean high water
B.mean low water
C.half-tide level
D.mean sea level

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