单项选择题
A.20000h. B.2000h. C.30000h.
A.过程层,间隔层和站控层 B.间隔层,站控层 C.间隔层,网络层和站控层
A.DC 220V/5A;50W(L/R=40ms) B.DC 250V/5A;50W(L/R=40ms) C.DC 110V/5A;50W(L/R=40ms)
A.<=0.5% B.<=0.2% C.<=0.1%
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