单项选择题
Deviation in a compass is caused by the（）.
A.vessel's geographic position B.vessel's heading C.earth's magnetic field D.influence of the magnetic materials of the vessel
单项选择题 Deviation is the angle between the（）.
单项选择题 Error may be introduced into a magnetic compass by（）.
单项选择题 Gyrocompass repeaters reproduce the indications of the master gyrocompass. They are（）.
