A.0.22dB/km B.0.31dB C.0.36dB/km D.0.4dB
A.填充式結(jié)構(gòu) B.骨架式結(jié)構(gòu) C.帶狀式結(jié)構(gòu)
A.800 B.1000 C.1200 D.1500