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

　　(2). A.34 Kbps B. 84 Kbps C. 64 Kbps D. 54 Kbps

　　(3). A.D channel B.A channel C.B channel D.C channel

　　(4). A.the method B.the number C.the service type D.the user type

　　(5). A.100000(10^5) B.1000(10^3) C.10000(10^4) D.100(10^2)

　　答案:

　　1:D,2:C,3:A,4:C,5:B

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　　Bluetooth is a universal radio interface in the (1) frequency band that enables portable celectronic devices (2) connect and communicate (3) via short range,ad hoc networks.Each unit can simultaneously communicate with up to (4) other units per piconet. Moreover,each unit can simultaneously (5) to several piconets,Bluetooth technology which apart from Ericsson,has gained the support of Nokia,IBM,Toshiba,Intel and many other manufactures,eliminates the need for wires,cables and connectors ...[查看详情]