单项选择题
The description Racon beside an illustration on a chart would mean a （）.
A.radar conspicuous beacon B.circular radiobeacon C.radar transponder beacon D.radar calibration beacon
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 （）.
单项选择题 The chart symbol indicating that the bottom is coral is （）.
