某医院确诊张某为癌症晚期，建议采取放射治疗，张某同意。医院在放射治疗过程中致张某伤残

A.Heeling magnet

B.Flinders bar

C.Fore-and-aft magnets

D.All of the above can be set on magnetic east or magnetic west headings

Which one of the followings is incorrect about magnetic compass？______.

A.The magentic compass is compulsory on my vessel

B.The magentic compass is prone to error

C.The magentic compass is always placed inside steel constructions

D.The magentic compass needs to be calibrated to compensate for local magnetic distortion

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

Which statement about the Flinders bar of the magnetic compass is CORRECT ________．

A.It compensates for the error caused by the vertical component of the Earth's magnetic field

B.It compensates for error caused by the heeling of a vessel

C.It compensates for quadrantal deviation

D.It is only needed in equatorial waters

Compass deviation is caused by ______.

A.magnetism from the earth’s magnetic field

B.misalignment of the compass

C.magnetism within the vessel

D.a dirty compass housing

Deviation in a compass is caused by the ______.

A.vessel’s geographic position

B.vessel’s heading

C.earth’s magnetic field

D.influence of the magnetic materials of the vessel

During the transition of the Earth's magnetic field ______.

A．the compass will become useless

B．man and animals will be confused as to directions

C．the magnetic strength of the Earth will disappear

D．the magnetic strength of the Earth will be stronger

Magnetic information on a chart may be ______.

A.found in the center(s) of the compass rose(s)

B.indicated by isogonic lines

C.found in a note on the chart

D.All of the above

Magnetic information on a chart may be ______.

A.found in the center(s) of the compass rese(s)

B.indicated by isogonic lines

C.found in a note on the chart

D.All of the above

In the fifth paragraph, the underlined word "it" refers to ______.

A．the earth's magnetic field

B．the sun

C．the built-in compass

D．the special way