单项选择题
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
单项选择题 A mid-channel buoy，if lighted，will show a（）.
单项选择题 A line on the Earth parallel to the equator is a（）.
单项选择题 A line of position formed by sighting two charted objects in line is called a(n)（）.
