A.1% B.2% C.3% D.4%
A.0.1~3 B.0.3~5 C.0.5~0.7 D.0.7~0.9
A.終端節(jié)點 B.傳輸節(jié)點 C.交換節(jié)點 D.傳輸系統(tǒng)