计算机等级考试四级笔试试卷及答案四之三

来源：计算机等级考试发布时间：2012-08-27 计算机等级考试视频评论

(87)What binary number is encoded with Differential Manchester in the

diagram below？(2 grades)

│┌─┐┌┐┌┐┌─┐┌┐┌┐┌┐┌─┐│

││││││││││││││││││

││││││││││││││││││

└┘└┘└┘└─┘└┘└┘└┘└─┘└┘

A)10110011100 B)11001100011

C)11000110010 D)00111001101

(88)Each host or router on the Internet has its own IP address.There

are four IP addresses as followings.Which IP address is erronedus？

A)189.132.2.1 B)255.255.255.0

C)198.73.265.50 D)192.0.0.3

(89)When should Frequency Division Multiplexing be used？

A)when the attenuation on a medium is greater than 25％。

B)when the white noise on the medium exceeds 50％of the medium's

bandwidth

C)when the achievable data rate of the medium exceeds the data

rate of the digital signals to be transmitted

D)when the useful bandwidth of the medium exceeds the required

bandwidth of the digital signals to be transmited

(90)The universe of hypertext servers that allow text,graphics,sound,

and other multimedia files to be viewed togather and navigated via

hypertext links.It is now the fastest growing area of the Internet.It

is

A)Gopher B)WWW C)E——mail D)FTP

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