单项选择题
A.20h至24h B.24h±1h C.24h±2h D.24h±4h
A.2mm B.3mm C.5mm D.10mm
A.50N/s±10N/s B.100N/s±10N/s C.50N/s±5N/s D.100N/s±5N/s
A.1350g±1g B.1350g±2g C.1350g±5g D.1350g±10g
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