单项选择题
A.2cm B.4cm C.6cm D.8cm
A.1mm B.2mm C.3mm D.5mm
A.1mm/4m B.2mm/4m C.3mm/4m D.5mm/4m
A.±0.1mm B.±0.2mm C.±0.4mm D.±0.5mm
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