单项选择题
A.均匀 B.不均匀 C.无规律 D.一大一小规律
A.≥1.2mm B.≥1.4mm C.≥1.6mm D.≥1.8mm
A.0.2~0.3mm B.0.3~0.5mm C.0.2~0.6mm D.0.6~1mm
A.≥4mm B.≥5mm C.≥6mm D.≥7mm
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