单项选择题
River currents tend to（）.
A.Pick up speed where the channel widens B.Run slower in the center of the channel C.Hug the inside of a bend D.Cause the greatest depth of water to be along the outside of a bend
单项选择题 Priming of the tides occurs（）.
单项选择题 Neap tides occur when the（）.
单项选择题 Neap tides occur only（）.
