单项选择题
A.T12或T13 B.35 C.16Mn D.45
A.粗锯齿 B.细锯齿 C.中锯齿 D.粗或中锯齿
A.0.5mm~1mm B.0.25mm~0.5mm C.0.05mm~0.1mm D.0.1mm~2mm