A.A CSU/DSU converts analog signals from a router to a leased line; a modem converts analog signals from a router to a leased line
B.A CSU/DSU converts analog signals from a router to a phone line; a modem converts digital signals from a router to a leased line
C.A CSU/DSU converts digital signals from a router to a phone line; a modem converts analog signals from a router to a phone line
D.A CSU/DSU converts digital signals from a router to a leased line; a modem converts digital signals from a router to a phone line

A.增加網(wǎng)絡(luò)帶寬
B.提高網(wǎng)絡(luò)可用性
C.降低網(wǎng)絡(luò)傳輸費(fèi)用
D.防止數(shù)據(jù)傳輸意外中止