A.variationB.deviationC.variation and deviationD.a corr……

单项选择题When adjusting a magnetic compass using the fore-and-aft permanent magnets，you should（）.

A.use the magnets one at a time，putting one in one side and then one on the opposite side，one step higher
B.use the magnets in pairs，starting at the top，with trays at the highest point of travel
C.use the magnets in pairs，from the bottom up，with the trays at the lowest point of travel
D.fill all the trays with magnets，then remove them one-by-one until the deviation is removed

单项选择题When adjusting a magnetic compass for error，a deviation table should be made（）.

A.before correcting for any deviation
B.after correcting for variation
C.after adjusting the fore-and-aft and athwartships permanent magnets
D.before the quadrantal correctors are placed on the compass

单项选择题When a vessel changes course from one cardinal heading to another cardinal heading whilea djusting the compass，which action should be taken?（）

A.The course change should be made rapidly to prevent transient induced magnetism while passing the intercardinal headings
B.After the new heading is reached，the vessel should steam on that course for at least two minutes before the adjustment
C.During the course change，you should gently tap the compass to remove any error caused by friction on the pivot bearing
D.After steadying on the new heading，the compass card should be slewed by a magnet and allowed to oscillate freely to remove any gaussin error

单项选择题When a magnetic compass is not in use for a prolonged period of time it should（）.

A.be shielded from direct sunlight
B.be locked into a constant heading
C.have any air bubbles replaced with nitrogen
D.have the compensating magnets removed

单项选择题What is the name of the movable，radial guide line used to measure direction on a radar?（）

A.Compass rose
B.Cursor
C.Plan position indicator
D.Variable range marker