单项选择题
A.0.1~0.25mm B.0.25~0.5mm C.0.5~1.0mm D.1.0~1.5mm
A.层次分明 B.长度均匀 C.结构紧凑 D.松紧适宜
A.+0.030mm B.+0.049mm C.0.030mm D.0.049mm
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