In more recent years，（）has been used by civilians in many new ways to determine positions，such as in automobile and boat navigation，hiking，emergency rescue，and precision agriculture and mining.

单项选择题By convention，the north seeking ends of a compass’ magnets are colored（）.

A.Black
B.Blue
C.Red
D.White

单项选择题Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called（）.

A.flux
B.poles
C.magnets
D.azimuth

单项选择题A vessel is heading magnetic east and its magnetic compass indicates a heading of 086°.Which action should be taken to remove this error during compass adjustment（）.

A.If the blue ends of the magnets are aft，and the fore-and-aft tray is at the top，you should add some magnets
B.If the blue ends of the magnets are aft you should lower the fore-and-aft tray
C.If the blue ends of the magnets are aft，and the fore-and-aft tray is at the top，you should reverse the magnets
D.If the blue ends of the magnets are forward，and the fore-and-aft tray is at the bottom，you should add some magnets

单项选择题A ship under construction or major repair will acquire permanent magnetism due to（）while sitting stationary in the earth’s magnetic field.

A.hammering and jarring
B.vibration and pounding
C.varying magnetic fields
D.stable or permanent magnetism of the ship

单项选择题When changing from a compass course to a true course you should apply（）.

A.variation
B.deviation
C.variation and deviation
D.a correction for the direction of current set