单项选择题
A current perpendicular to a vessel’s track has the greatest effect on the vessel’s course made good（）.
A.at high vessel speeds B.at low vessel speeds C.in shallow water D.in deep water
单项选择题 When compared to air temperature,which factor is most useful in predicting fog?（）
单项选择题 Radiation fog is more commonly encountered in（）.
单项选择题 Maintenance of charts and nautical publications up to date is a statutory requirement under the（）Convention.
