思科认证考试

Which spread spectrum technology does the 802.11b standard define for operation?（）A、IRB、DSSSC、FHSSD、DSSS and FHSSE、IR, FHSS, and DSSS

题目

Which spread spectrum technology does the 802.11b standard define for operation?（）

  • A、IR
  • B、DSSS
  • C、FHSS
  • D、DSSS and FHSS
  • E、IR, FHSS, and DSSS
参考答案和解析
正确答案:B
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相似问题和答案

第1题：

●In the following essay，each blank has four choices．Choose the best answer and write down on the answer sheet．

Spread spectrum simply means that data is sent in (66) pieces over a number of the discrete frequencies available for use at any time in the specified range．Devices using (67) spread spectrum(DSSS)communicate by splitting each (68) of data into several parts and sending them concurrently on different (69) ,DSSS uses a lot of the available (70) ，about 22 megahertz(MHz)．

(66) A．small

B．high

C．low

D．long

(67) A．direct-sequence

B．discrete-sequence

C．duplicate-sequence

D．dedicate-sequence

(68) A．data

B．byte

C．packet

D．bit

(69) A．bits

B．frequencies

C．packets

D．messages

(70) A．rate

B．velocity

C．bandwidth

D．period


正确答案：A,B,B,B,C
【解析】简单地来说，扩频就是在一个可以随时使用的特定频率范围内，把数据用小块在大量不连续的频率上同时发送。使用直序扩频的设备相互之间通信是通过把每个字节的数据分成几个部分在不同的频率上同时传送。直序扩频使用了大约22 Mb的有效带宽。

第2题：

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

Spread spectrum simply means that data is sent in(66)pieces over a number of the discrete frequencies available for use at any time in the specified range. Devices using(67) spread spectrum (DSSS)communicate by splitting each(68)of data into several parts and sending them concurrently on different (69), DSSS uses a lot of the available(70), about 22 megahertz (MHz).

A．small

B．high

C．low

D．long


正确答案：A

第3题：

根据下面的文字资料回答 71～75 题 In the following essay．each blank has four choices．Choose the best answer and write down on the answer sheet．

Spread spectrum simply means that data is sent in（ 1 ）pieces over a number of the discrete frequencies available for use at any time in the specified range．Devices using（ 2 ） spread spectrum(DSSS)communicate by splitting each（ 3 ）of data into several parts and sending them concurrently on different（ 4 ），DSSS uses a lot of the available（ 5 ），about 22 megahertz(MHz)．

第71题：文中（ 1 ）处正确的答案是（ ）。

A．small

B．high

C．low

D．long


正确答案：A
简单地来说，扩频就是在一个可以随时使用的特定频率范围内，把数据用小块在大量不连续的频率上同时发送。使用直序扩频
图6网卡的简单框架
的设备相互之间通信是通过把每个字节的数据分成几个部分在不同的频率上同时传送。直序扩频使用了大约22 Mb的有效带宽。

第4题：

Like no previous technology, mobile technology has spread______an unprecedented pace in the last few years.

A.at
B.in
C.on
D.with

答案：A
解析：
本题考查介词用法辨析。题目意为“与之前的技术不同，移动技术在过去几年中以前所未有的速度发展。”根据题干，at a pace为固定搭配，意为“以……的速度”，因此A选项正确。
　　

第5题：

Spread spectrum simply means that data is sent in small pieces Over a number of the(46)frequencies available for use at any time in the specified range. Devices using(47)spread spectrum (DSSS)communicate by(48)each byte of data into several parts and sending them concurrently on different(49). DSSS uses a lot of the available(50), about 22 megahertz (MHz).

A．continuous

B．high

C．low

D．discrete


正确答案：D

第6题：

The introduction of the printing technology to England helped to spread English into many countries and places over the world so that it has become the most important international language in the present day.()


参考答案：错误

第7题：

Which of the following is a performance optimization technology?()

A.QoS

B.Trunking

C.Spanning

D.VoIP


参考答案：A

第8题：

Which is the element responsible for rising wage inequality?

A．Technology as a more irresistible force.

B．Technology and globalization.

C．Technology and automation.

D．Social class in white and blue-collars.


正确答案：B
解析：原文中play a role in．．．的意思是“在……中起作用”。根据定位句中的also和bigger可以知道，作者是在拿technology与前一句的globalization作比较，因此两者均是rising wage inequality的原因。故本题答案为B。

第9题：

Which spread spectrum technology does the 802.11b standard define for operation()。

A.IR

B.DSSS

C.FHSS

D.DSSS and FHSS

E.IR, FHSS, and DSSS


参考答案：B

第10题：

He has made a discovery, ___ of great importance to the progress of science and technology.

A.which I think it is
B.which I think is

C.think which is

D.of which I think it is

答案：B
解析：
本题主要考查定语从句，全句意为“他有了一项新的发现，我认为这项发现对科技进步非常重要。”I think 作插入语，去掉不影响句意，which在这里作关系代词代替discovery，放在句首在从句中作主语，即：I think the discovery（which）is of great importance..。不需要再有it作形式主语。

考点
定语从句

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