单项选择题
A.the compass heading is in line with the lubber's line
B.there is no lost motion in the gimbal rings
C.no change of heading by compass is observed if you raise and lower the heeling magnet
D.the gimbal rings do not strike the compass frame when they are tilted
单项选择题 The vertical component of the Earth’s magnetic field causes induced magnetism in vertical soft iron. This changes with latitude. What corrects for this coefficient of the deviation? （）
单项选择题 The vertical angle between the horizontal and the magnetic line of force is the（）.
单项选择题 The total magnetic effects which cause deviation of a vessel’s compass can be broken down into a series of components which are referred to as（）.