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（）.
A.divisional parts B.coefficients C.fractional parts D.equations
单项选择题 The standard magnetic compass heading differs from the true heading by（）.
单项选择题 The reaction of a gyrocompass to an applied force is known as（）.
单项选择题 The quadrantal spheres are used to（）.
