单项选择题
The maximum difference between mean time and apparent time is （）.
A.equal to the longitude expressed in time units B.about 16 minutes C.the difference between the GHA of mean sun and the first point of Aries D.15°of arc
单项选择题 The description Racon beside an illustration on a chart would mean a （）.
单项选择题 The compass rose on a nautical chart indicates both variation and （）.
单项选择题 The charts sold are of （）.
