单项选择题
A.正负1% B.正负2% C.正负3% D.正负4%
A.大于等于3000MΩ B.大于等于5000MΩ C.大于等于10000MΩ D.大于等于20000MΩ
A.小于等于0.5%/年 B.小于等于0.6%/年 C.小于等于0.7%/年 D.小于等于0.8%/年
A.80%~110% B.80%~100% C.90%~100% D.90%~110%
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