单项选择题
A.1m/sB.1.5m∕sC.2m∕sD.2.5m∕s
A.5%~6%B.6%~7%C.7%~9%D.9%~10%
A.4~5B.5~6C.6~7D.7~8
A.5~10B.10~15C.15~20D.20~25
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