单项选择题
A.have lows lower than normal and highs higher than normal B.have lows higher than normal and highs lower than normal C.are unpredictable D.occur in the spring of the year
Set of current is（）.A.its velocity in knotsB.direction ...
单项选择题Set of current is（）.
A.its velocity in knots B.direction from which it flows C.estimated current D.direction toward which it flows
Scouring is the result of（）.A.interruption of the norma...
单项选择题Scouring is the result of（）.
A.interruption of the normal current flow by the footing B.elevating in mud-slide zones C.penetrating rapidly through a hard crust into weaker soils D.extracting legs from soils with high cohesion
River currents tend to（）.A.pick up speed where the chan...
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
