单项选择题
A.T7A B.40Cr C.45号钢
A.ω=30° B.ω=18°-30° C.ω=40° D.ω=15°
A.γ。=20° B.γ。=30° C.γ。=40°
A.三等砝码 B.四等砝码 C.五等砝码 D.1/10000 E.1/20000 F.1/400
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