单项选择题
Magnetic heading differs from compass heading by（）.
A.compass error B.true heading C.variation D.deviation
单项选择题 Magnetic dip is a measurement of the angle between the（）.
单项选择题 Magnetic compass deviation（）.
单项选择题 Knowing the compass heading that is 90°to the side of a ship will enable the operator of a survival craft to initially steer（）.
