单项选择题
A.<60%RH B.<80%RH C.<50%RH D.<20%RH
A.1-2S B.1-3S C.1-4S D.1-5S
A.10-20mm B.20-30mm C.30-40mm D.10-15mm
A.≤3mm B.≤4mm C.≤5mm D.≤6mm
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