单项选择题
If a magnetic compass is not affected by any magnetic field other than the Earth’s，which statement is TRUE?（）.
A.Compass error and variation are equal B.Compass north will be true north C.Variation will equal deviation D.There will be no compass error
单项选择题 If the compass heading and the magnetic heading are the same then（）.
单项选择题 If the gyrocompass error is east，what describes the error and the correction to be made to gyrocompass headings to obtain true headings?（）.
单项选择题 Magnetic heading differs from compass heading by（）.
