A.Quadrantal spheresB.Heeling magnetsC.Flinders barD.Fo……

单项选择题Which compensates for errors introduced when the vessel heels over（）.

A.The soft iron spheres on the arms of the binnacle
B.Magnets placed in trays inside the binnacle
C.A single vertical magnet beneath the compass
D.The Flinders bar

单项选择题When relieving the helm，the new helmsman should know the（）.

A.Course per magnetic steering compass
B.Gyro error
C.Variation
D.Maximum rudder angle previously used

单项选择题When crossing the magnetic equator the（）.

A.Flinders bar should be inverted
B.Heeling magnet should be inverted
C.The quadrantal spheres should be rotated 180°
D.Flinders bar should be moved to the opposite side of the binnacle

单项选择题What is used to correct for both induced and permanent magnetism，and consequently must be readjusted with radical changes in latitude（）.

A.Flinders bar
B.Soft iron spheres
C.Fore-and-aft permanent magnets in their trays
D.Heeling magnet

单项选择题What is the basic principle of the magnetic compass（）.

A.Magnetic materials of the same polarity repel each other and those of opposite polarity attract
B.The Earth's magnetic lines of force are parallel to the surface of the Earth
C.Magnetic meridians connect points of equal magnetic variation
D.The compass needle（s）will，when properly compensated，lie parallel to the isogonic lines of the Earth