如图3-1所示为曼彻斯特编码，表示的数据可能为(1)，这种编码适用的网络是(2)。为了在广域网上高速传输数字信号，一般可用的编码方式是(3)，其编码效率为(4)。设某编码体制的编码方法为：输入数据(m=1，2，…)，发送时首先计算bm=(aM+bm-1)MOD2，发送的编码为Cm=bm-bm-1，收到的编码为Cm，其译码方法可表示为(5)。

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Multipurpose Internet Mail Extension(MIME)is a(71)document messaging standard in the Internet enviroment, with MIME, users can send(72)Email messages that include audio, video, graphices, and text to any other user of a TCP/IP network. Richtext information can also be(73)into messages. It defines the fonts, formats, and(74)features of a document so the document can be easily(75)on many different types of systems.

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For each blank, choose the best answer from the four choices and write down on the answer sheet.

(66)is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.

(67)is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.

(68)functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.

(69)is the popular LAN developed under the direction of the IEEE 802.5.

(70)is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.

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