单项选择题
A.T10钢 B.20号钢 C.45号钢 D.65Mn钢
A.≤16mm B.≤17mm C.≤18mm D.≤19mm
A.(250±2)mm B.(260±2)mm C.(270±2)mm D.(280±2)mm
A.≤0.04mm B.≤0.03mm C.≤0.02mm D.≤0.01mm
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