单项选择题
A.45°～52° B.65°～72° C.90° D.75°-85°
A.150g-550g B.250g-650g C.350g-750g D.450g-850g
A.硬质合金 B.一般钢铁材料 C.碳素工具钢及合金工具钢 D.弹簧钢
A.20mm B.12mm C.7mm D.16mm
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