A relative bearing is always measured from（）.……

单项选择题A preferred-channel buoy will show a（）.

A.white light whose characteristic is Morse (A)
B.group-occulting white light
C.composite group-flashing (2 + 1) white light
D.composite group-flashing (2 + 1) red or green light

单项选择题A preferred-channel buoy may be（）.

A.lettered
B.spherical
C.showing a white light
D.All of the above

单项选择题A plane that cuts the Earth’s surface at any angle and passes through the center will always form（）.

A.the equator
B.a great circle
C.a small circle
D.a meridian

单项选择题A plane that cuts the Earth’s surface and passes through the poles will always form（）.

A.the equator
B.a loxodromic curve
C.a small circle
D.a meridian

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

A.Great circle
B.Equator
C.Small circle
D.Meridian