单项选择题
A.0.2mB.0.4mC.0.6mD.0.8m
A.40m,10m,100mB.40m,15m,100mC.50m,15m,100mD.40m,10m,80m
A.空气B.氮气C.真空D.氦气
A.沉孔B.铸造圆角C.倒角D.局部放大图
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