A.傳輸介質(zhì) B.信道 C.數(shù)據(jù) D.節(jié)點(diǎn)設(shè)備
A.4400Hz B.3200Hz C.600Hz D.3800Hz
A.信元交換 B.電路交換 C.虛電路分組交換 D.數(shù)據(jù)報(bào)分組交換