单项选择题
A.0.43 B.0.2 C.0.6 D.0.8
A.层流;紊流 B.紊流;层流 C.层流;层流 D.紊流;紊流
A.0.7 B.0.2 C.0.5 D.0.6
A.0.5 B.0.2 C.0.3 D.0.4
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