航海英语磁罗经与陀螺罗经的使用单项选择题每日一练(2018.04.26)

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
Quadrantal error in a gyrocompass has its GREATEST effect（）.
A.in high latitudes
B.near the equator
C.on north or south headings
D.on intercardinal headings
单项选择题
The permanent magnetism of a vessel may change in strength due to（）.
A.a collision with another vessel
B.being moored on a constant heading for a long period of time
C.being struck by lightning
D.All of the above
单项选择题
What are the only magnetic compass correctors that correct for both permanent and induced effects of magnetism?（）
A.Quadrantal spheres
B.Heeling magnets
C.Athwartships magnets
D.Fore-and-aft magnets
单项选择题
Magnetic variation changes with a change in（）.
A.the vessel's heading
B.sea conditions
C.seasons
D.the vessel's position