单项选择题
A.Remove deviation on the intercardinal headings
B.Remove deviation on the cardinal compass headings
C.Remove heeling error
D.Compensate for induced magnetism in vertical soft iron
单项选择题 The MOST important feature of the material used for making the binnacle of a standard magnetic compass is that it is（）.
单项选择题 The most accurate method of determining gyrocompass error while underway is by（）.
单项选择题 The magnetism in the various structures of a ship changing as a result of cruising，vibration，or aging is termed（）.