A plane perpendicular to the polar axis will never form what line on the Earth’s surface? （）

A parallel of latitude other than the equator is a（）.

A.great circle
B.loxodromic curve
C.small circle
D.gnomonic curve

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A nun buoy will（）.

A.be green in color
B.have an even number
C.be left to port when entering from seaward
D.be cylindrical in shape

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