单项选择题
A.0.5% B.0.8% C.1% D.1.5%
A.水泥套管B.铸铁套管C.金属套管D.瓷质套管
A.0.1Mpa B.0.2MPa C.0.3Mpa D.0.4MPa
A.4m B.5m C.6m D.8m
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