单项选择题
A.permanent magnetism B.subpermanent magnetism C.induced magnetism D.variable magnetism
The line which connects the points of zero magnetic dip...
单项选择题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
The Flinders bar and the quadrantal spheres should be t...
单项选择题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
The Flinders bar on a magnetic compass compensates for ...
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
