A.τ=P/(πDH) B.τ=P/(2dH) C.τ=P/(πdH) D.

A.τ=P/(πDH) B.τ=P/(2dH) C.τ=P/(πdH) D.

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A.21.5~22.5m/s B.16.5~17.5m/s C.14.5~15.5m/s D.10~11m/s

A.21.5~22.5m/s B.16.5~17.5m/s C.14.5~15.5m/s D.10~11m/s

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