单项选择题
The only cylindrical chart projection widely used for navigation is the （）.
A.Lambert conformal B.Mercator C.azimuthal D.gnomonic
单项选择题 The numeral in the center of a wind rose circle on a pilot chart indicates the （）.
单项选择题 The maximum difference between mean time and apparent time is （）.
单项选择题 The description Racon beside an illustration on a chart would mean a （）.
