单项选择题
A.金刚石B.陶瓷C.CBND.45钢
A.20~30nmB.20~30mmC.40~50nmD.40~50mm
A.5mmB.0.5mmC.5µmD.0.5µm
A.0.1~0.2µm/250mmB.1~2µm/250mmC.0.1~0.2µm/500mmD.1~2µm/500mm
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