单选题A condition where two currents meet at the downstream end of a middle bar can be determined by a（）.Asmall whirlpoolBsmooth patch of waterCV-shaped ripple with the point of the V pointing downstreamDV-shaped ripple with the point of the V pointing upstream
单选题
A condition where two currents meet at the downstream end of a middle bar can be determined by a（）.
A
small whirlpool
B
smooth patch of water
C
V-shaped ripple with the point of the V pointing downstream
D
V-shaped ripple with the point of the V pointing upstream
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