单项选择题
A.2%~4% B.5%~10% C.11%~15% D.15%~20%
A.±0.2% B.±0.5% C.±1% D±1.5%
A.不允许B.允许2小时C.允许短时间D.允许1小时
A.5 B.10 C.15 D.20
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