A.甲用戶用來(lái)發(fā)送E-MAIL的服務(wù)器上 B.乙用戶用來(lái)收E-MAIL的服務(wù)器上 C.甲用戶的計(jì)算機(jī)上 D.乙用戶的計(jì)算機(jī)上
A.同時(shí)傳遞數(shù)據(jù)語(yǔ)音且上下數(shù)據(jù)帶寬對(duì)稱(chēng) B.同時(shí)傳遞數(shù)據(jù)語(yǔ)音且上下數(shù)據(jù)帶寬不對(duì)稱(chēng) C.只傳數(shù)據(jù)上下對(duì)稱(chēng) D.只傳數(shù)據(jù)上下不對(duì)稱(chēng)