单项选择题
A.vertical movement of the water B.horizontal movement of the water C.density changes in the water D.None of the above
A structure，usually made of stone，or cement pilings，whi...
单项选择题A structure，usually made of stone，or cement pilings，which extends from the bank at approximately right angles to the current is called a（）.
A.dike B.revetment C.cutoff D.crib
A stream of water immediately surrounding a moving vess...
单项选择题A stream of water immediately surrounding a moving vessel’s hull，flowing in the same direction as the vessel is known as（）.
A.directional current B.forward current C.propeller current D.wake current
