单项选择题
A.2960 B.1460 C.970 D.720
A.0.35~0.5mm B.0.5~1mm C.1~1.5mm D.1.5~2mm
A.1/10~1/4 B.1/4~1/2 C.1/3~3/4 D.1/2~9/10
A.1 B.1.5 C.2 D.2.5
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