单项选择题

A.needles are nearly in line with the meridianB.vessel ……

The greatest directive force is exerted on the magnetic compass when the（）.

A.needles are nearly in line with the meridian
B.vessel is near the magnetic poles
C.variation is near zero
D.vessel is near the magnetic equator

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单项选择题The Flinders bar on a magnetic compass compensates for the（）.

A.induced magnetism in vertical soft iron
B.induced magnetism in horizontal soft iron
C.permanent magnetism in ship's steel
D.vessel's inclination from the vertical

单项选择题The error in a magnetic compass caused by the vessel’s magnetism is called（）.

A.variation
B.deviation
C.compass error
D.bearing error

单项选择题The directive force of a gyrocompass（）.

A.increases with latitude，being maximum at the geographic poles
B.decreases with latitude，being maximum at the geographic equator
C.is greatest when a vessel is near the Earth's magnetic equator
D.remains the same at all latitudes

单项选择题The difference between magnetic heading and compass heading is called（）.

A.variation
B.deviation
C.compass error
D.drift

单项选择题The compass heading of a vessel differs from the true heading by（）.

A.compass error
B.variation
C.magnetic dip
D.deviation