单项选择题
The velocity of a rotary tidal current will be decreased when the Moon is（）.
A.at apogee B.new C.full D.All of the above
单项选择题 The type of current which will have the greatest effect on the course made good for your vessel is（）.
单项选择题 The two most effective generating forces of surface ocean currents are（）.
单项选择题 The tide is（）.
