A.>98% B.>99% C.>99.9% D.全部暢通
A.1s B.3s C.5s D.10s
A.0.2Erl(正常)和0.4Erl(異常) B.0.3Erl(正常)和0.6Erl(異常) C.0.4Erl(正常)和0.8Erl(異常) D.0.4Erl(正常)和0.6Erl(異常)