A.國(guó)際干線傳愉系統(tǒng) B.市際干線傳愉系統(tǒng) C.省際干線傳愉系統(tǒng) D.縣際干線傳愉系統(tǒng)
A.4900km B.5900km C.6800km D.7900km
A.接入網(wǎng) B.短途網(wǎng) C.長(zhǎng)途網(wǎng) D.傳輸網(wǎng)