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單項選擇題

The magnetism in the various structures of a ship changing as a result of cruising，vibration，or aging is termed（）.

A.permanent magnetism
B.subpermanent magnetism
C.induced magnetism
D.variable magnetism

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單項選擇題

The line which connects the points of zero magnetic dip is（）.

A.An agonic line
B.The magnetic equator
C.A magnetic meridian
D.All of the above

單項選擇題

The Flinders bar and the quadrantal spheres should be tested for permanent magnetism at what interval（）.

A.They are not subject to permanent magnetism; no check is necessary
B.Semiannually
C.Annually
D.Every five years