单项选择题
The velocity of the wind，its steady direction，and the amount of time it has blown determines a wind driven current’s（）.
A.temperature B.density C.deflection D.speed
单项选择题 The velocity of the current in large coastal harbors is（）.
单项选择题 The velocity of a rotary tidal current will be decreased when the Moon is（）.
单项选择题 The type of current which will have the greatest effect on the course made good for your vessel is（）.
