软件水平考试网络工程师英语复习练习题10套

第1套

ISDN,which stands for Integrated Services Digital Network, is a system of digital phone connections, which has been available for over a decade.This system allows data to be transmitted simultaneously across the world using (1) digital connectivity.With ISDN,voice and data are carried by bearer channels occupying a  bandwith of  (2) (bits per second).Some switches limit B channels to  capacity of 56 Kbps.A data channel (3) handles signaling at 16Kbps  or 64Kbps,depending on (4) .Note that,in ISDN terminology,"k"  means (5),and not 1024(2^10) as in many computer  applications;therefore,a 64Kbps channel carries data at a rate of  64000bps. A new set of standard prefixes has recently been created  to handle this. Under this scheme,"K"(Kilo) means 1000(10^3),"M" (Mega) means 1000000(10^6),and soon ,and "Ki"(Kibi) means 1024 (2^10),"Mi" (Mebi) means 1048576(2^20).and soon。 (1). A.Multi-ends   B.circle    C.indirect     D.end-to-end
(3). A.D channel    B.A channel  C.B channel  D.C channel
(5). A.100000(10^5)   B.1000(10^3)    C.10000(10^4)    D.100(10^2)