单项选择题
A.32V B.24V C.110V D.220V
A.灰口铸铁 B.球墨铸铁 C.可锻铸铁 D.钢管
A.0.1ml B.0.2ml C.0.3ml D.0.4ml
A.±3% B.±2% C.±1% D.±0.5%
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