单项选择题
A.50mm±0.5mm B.50mm±1mm C.50mm±1.5mm D.50mm±2mm
A.±0.02mm B.±0.03mm C.±0.04mm D.±0.05mm
A.标签 B.气体成分检测报告 C.试用 D.外观
A.3% B.4% C.5% D.6%
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