单项选择题 In which voyage, between two points, is the rhumb line distance not approximately the same as the great circle distance?（）.

单项选择题 Intertropical convergence zone over south Phillippine passing over Mindanao northern Sulu and Palawan. This paragraph is likely to be under the heading of（）.

单项选择题 It takes about 12 seconds to reverse（）full speed ahead（）speed astern.