A.numberedB.letteredC.greenD.redA spherical buoy may be……

单项选择题A special purpose buoy shall be（）.

A.lighted with a white light
B.striped black and red
C.lighted with a red light
D.yellow

单项选择题A special mark (yellow buoy)，if lighted，may exhibit which light rhythm?（）

A.Flashing
B.Morse A
C.Equal interval
D.Occulting

单项选择题A SEAMARK，I.E. A BUOY，INDICATING THE NORTH，EAST，SOUTH OR WEST FROM A FIXED POINT，E.G. A WRECK is（）.

A.Entrance buoy
B.New buoy
C.Port buoy
D.Cardinal buoy

单项选择题A rock and sand structure extending from the bank of the river toward the channel is known as a（）.

A.wingdam
B.towhead
C.cutoff
D.landwall

单项选择题A relative bearing is always measured from（）.

A.true north
B.magnetic north
C.the vessel's beam
D.the vessel's head