单项选择题
A.9.5m B.10m C.10.2m D.10.5m
A.168mm B.219mm C.250mm D.240mm
A.6 B.7 C.8 D.9
A.圆柱齿轮 B.斜齿轮 C.圆柱、斜齿轮 D.滑轮
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