北京电大官网

篇一：北京电大网站操作手册

电大网络平台使用手册 常用网站：

我们经常需要浏览的就是中央电大和北京电大的网站。

1、中央电大：

选择“教师教学平台入口”

输入用户名：用户名：mmafj

找到“我的课程”（如下）

密码：m1234

从专科、本科课程的下拉菜单里找自己的专业和课程。我们只要在本科和专科栏目里找到“社会工作”专业即可，里面会有我们开设的课程。对于北京电大开设的（即省开）课程，在中央电大的网站上是找不到的，参考资料仅在北京电大在线学习平台里。

2、中央电大在线：

用户名：jiaoxuezhidao 密码：ky123456

3、中央电大形成性测评系统：

4、北京电大：（详细操作方法见后续的说明）

5、北京电大在线：

用户名：教学指导密码：123456

6、北京电大邮箱：

7、开放教育学院：

8、开院在线平台：

用户名：教学指导 密码：123456

*各位教师如有需要，也可进行教师注册，注册后，需电话联系教学秘书，进行权限批复。

中央电大在线学习平台用户名：mmafj 密码：m1234

北京电大在线学习平台用户名：教学指导 密码：m123456

导学教师、各位专业责任教师、秘书 电话沟通（在北京电大在线学习平台上找到自己所教的科目，上面有责任教师介绍及联系方式） 蓝卓移动校园网：短信平台 开放学院工作群：127503126（QQ群） 开放学院教师工作群：127503126 （QQ群） 教学指导部公共邮箱： [email protected]

一、登录系统

教师打开IE浏览器，在地址栏中输入北京电大学习平台的网址：http://school.btvu.org或http://school.bjou.org，在页面的右上角选择“教师登录”输入用户名、密码登录。如图1-1：

图1-1

登录系统后在【我的课程】页面点击“管理测试”如图1-2：

图1-2

如果用户拥有形考平台相应权限，则可以直接进入“北京电大在线考试平台”，如没有权限系统会显示登陆页面，说明没有权限登录“考试平台”。如图1-3所示。

图1-3

二、评阅作业

登录系统后，点击如图2-1所示的【功能列表】栏中的【评阅 作业】。

图2-1

在这里老师可以对学生所做的作业进行评分，如图2-2：

图2-2

选择相应的“学期”、“作业名称”、“班级名称”和“作业状态”后在“任务列表”框中会显示出所有满足条件学生的作业列表，点击

【评阅】可以对学生的作业进行评分。如图2-3所示： 注意：已评阅的作业只能进行查看不可以再次评阅。

图2-3

学生的基本信息和作业标题分别显示在栏目的上方。“单选题”、“多选题”“填空题”等大题名称会显示在作业标题的下方。“单选题”、“多选题”、“判断题”、“组合题”这些客观题不需要评分，但是可以分别点击查看学生的得分情况。其它主观题题型需要逐一评分，例如“填空题”如图2-4：

篇二：北京电大计算机网络-作业参考答案

中央广播电视大学计算机网络技术专业（专科）

《计算机网络（专）》课程作业（1）

一、名词解释

1．计算机网络

答:所谓计算机网络就是利用通信设备和线路将地理位置不同、功能独立的多个计算机系互联起来，并在网络操作系统等软件的支持下实现网络中资源（硬件资源、软件资源和数据信息资源）共享和信息传递的系统。

2．资源子网

答:计算机网络的硬件部分主要完成数据处理和数据通信两大功能，由此可以将其分为资源子网和通信子网两部分。

资源子网负责网络数据处理并为网络用户提供网络服务和网络资源，它主要由联网的主机、终端、终端控制器、联网外设等部分组成。

3．通信信道

答:通信信道(Communication Channel)是数据信号传输的通路，在计算机网络中信道分为物理信道和逻辑信道。物理信道指用于传输数据信号的物理通路，它由传输介质与有关通信设备组成；逻辑信道指在物理信道的基础上，发送与接收数据信号的双方通过中间结点所实现的逻辑通路，由此为传输数据信号形成的逻辑通路。逻辑信道可以是有连接的，也可以是无连接的。 物理信道可根据传输介质的不同而分为有线信道和无线信道，也可按传输数据类型的不同分为数字信道和模拟信道。

4．基带传输

答：在数据通信信道中直接传输数据的基带信号的通讯方式称为基带传输。

5. IP地址

答:所谓IP地址就是给每个连接在Internet上的主机分配的一个32bit地址。按照TCP/IP协议规定，IP地址用二进制来表示，每个IP地址长32bit，比特换算成字节，就是4个字节。为了方便人们的使用，IP地址经常被写成十进制的形式，中间使用符号“.”分开不同的字节。IP地址的这种表示法叫做“点分十进制表示法”。

6．地址解析

答:所谓地址解析（address resolution）就是主机在发送帧前将目标IP地址转换成目标MAC地址的过程。

7. 网络互联

答:网络互联是指通过采用合适的技术和设备,将不同地理位置的计算机网络连接起来,形成一个范围更大、规模更大的网络系统，实现更大范围的资源共享和数据通信。它有4中类型：

（1）局域网时间的互联（LAN--LAN）:局域网之间的互联网分为同构网的互联和异构网的互联。

8．路由表

答:路由表或称路由择域信息库（RIB）是一个存储在路由器或者联网计算机中的电子表格（文件）或类数据库。路由表存储着指向特定网络地址的路径（在有些情况下，十进制的数据也附属在路径上）。路由表中含有网络周边的拓扑信息。路由表建立的主要目标是为了实现路由协议和静态路由选择。

二、简答题

1．什么是计算机网络？计算机网络的发展主要经历了哪四代？

答：所谓计算机网络就是利用通信设备和线路将地理位置不同、功能独立的多个计算机系互联起来，并在网络操作系统等软件的支持下实现网络中资源（硬件资源、软件资源和数据信息资源）共享和信息传递的系统。

计算机网络的发展主要经历了哪四个阶段是：

（1）第一阶段——面向终端的计算机网络；

（2）第二阶段——计算；机通信网络；

（3）第三阶段——计算机互联网络

（4）第四阶段——宽带综合业务数字网（信息高速公路）。

2．计算机网络主要由哪几部分组成的？

答：一个完整的计算机网络系统是由网络硬件系统和网络软件系统组成的。

3．何为单工通信、半双工通信和全双工通信？各有何特点？

答：（1）单工通信是指通信只在一个方向上发生，如电视传播。

（2）双工通信是指在相对的方向上可以同时传输信息，如电话通信。

（3）半双工通信可以实现双向的通信，但不能在两个方向上同时进行，必须轮流交替地进行。如步话机（对讲机）通信。

4．什么是网络体系结构？

答：网络体系结构式为了完成计算机件的通信合作，把每台计算机互联的功能划分成有明确定义的层次，规定了同层次进程通信的协议及邻层之间的接口及服务，这些同层进程通信的协议及相邻层的接口统称为计算机网络体系结构。

5．什么是协议？它由几部分组成？

答：协议是实现对等层实体间的通信而建立、制订的通信规则或是说约定的集合。其中包括：语义、语法、同步。

6. 什么是网络互联，它有几种类型？

答:网络互联是指通过采用合适的技术和设备,将不同地理位置的计算机网络连接起来,形成一个范围更大、规模更大的网络系统，实现更大范围的资源共享和数据通信。它有4中类型：

（1）局域网时间的互联（LAN--LAN）:局域网之间的互联网分为同构网的互联和异构网的互

联。

（2）局域网与城域网的互联（LAN--MAN）

（3）局域网与广域网的互联（LAN—WAN--LAN）

（4）广域网与广域网的互联（WAN--WAN）

三、应用题

如果HDTV高清视频的分辨率为1024×768，每个像素需要24bit，帧传输速率为30帧/秒，则在理论上为2.5GHz带宽，信噪比为30dB的信道上能否实现实时传输HDTV视频？ 答：(1)实时传输HDTV视频所需要的信道带宽至少应该为

每帧像素总数×每个像素需要位数×帧传输速率/（1024×1024）(Mbps)，即：

1024×768×24×30/(1024×1024)=540Mbps

(2)理论上，2.5GHz带宽，信噪比为30dB的信道的信道容量C=W×log2(1+S/N), 由10lg(S/N)=30dB可知，信噪比S/N=1000，又知W=2.5G=2500M

所以，C=W×log2(1+S/N)=2500× log2(1+1000)=2500×10=25000Mbps

由于25000Mbps>540Mbps, 所以可得下述结论：在理论上为2.5GHz带宽，信噪比为30dB的信道上能实现实时传输HDTV视频。

中央广播电视大学计算机网络技术专业（专科）

《计算机网络（专）》课程作业（2）

一、名词解释

1．通信子网

答：计算机网络的硬件部分主要完成数据处理和数据通信两大功能，由此可以将其分为资源子网和通信子网两部分。

通信子网负责网络数据传输、转发等通信处理任务，它主要由通信控制处理机、通信线路与信号变换设备组成。

2．局域网

答：计算机局域网是把分布在数公里范围内的不同物理位置的计算机设备连在一起，在网络软件的支持下可以相互通讯和资源共享的数据通信系统。

3．信号

答：信号是数据在传输过程中的具体物理表示形式，具有确定的数据的物理描述，如电压、磁场强度等。

4．比特率、波特率

答：比特率是指信道每秒钟传送的二进制位数，用 b / s 表示（b表示bit）。（每秒钟通过信道传输的信息量称为位传输速率简称比特率。比特率表示有效数据的传输速率。） 波特率是指数据信号对载波的调制速率，它用单位时间内载波调制状态改变的次数来表示，其单位是波特（Baud）。（在信息传输通道中，携带数据信息的信号单元叫码元，每秒钟通过信道传输的码元数称为码元传输速率，简称波特率。）

5．网络体系结构

答：网络体系结构式为了完成计算机件的通信合作，把每台计算机互联的功能划分成有明确定义的层次，规定了同层次进程通信的协议及邻层之间的接口及服务，这些同层进程通信的协议及相邻层的接口统称为计算机网络体系结构。

6．协议

答：协议是实现对等层实体间的通信而建立、制订的通信规则或是说约定的集合。其中包括：语义、语法、同步。

7．网关

网关(Gateway)又称网间连接器、协议转换器。网关在传输层上以实现网络互连，是最复杂的网络互连设备，仅用于两个高层协议不同的网络互连。

8．广域网

答：广域网（WAN，Wide Area Network）也称远程网。通常跨接很大的物理范围，所覆盖的范围从几十公里到几千公里，它能连接多个城市或国家，或横跨几个洲并能提供远距离通信，形成国际性的远程网络。

二、简答题

1．组建计算机网络的硬件设备主要有哪些？

答：计算机网络的硬件部分主要完成数据处理和数据通信两大功能，由此可以将其分为资源子网和通信子网两部分。

（1）资源子网：负责网络数据处理并为网络用户提供网络服务和网络资源，它主要由联网的主机、终端、终端控制器、联网外设等部分组成。

（2）通信子网：负责网络数据传输、转发等通信处理任务，它主要由通信控制处理机、通信线路与信号变换设备组成。

组建计算机网络通常需要的其它硬件设备还有：网络适配器（网卡）、中继器、集线器（HUB）、网桥、服务器、路由器及传输介质等。

3．计算机网络的软件系统主要有哪些？

答：计算机网络的软件包括：网络协议、网络通信软件、网络操作系统、网络管理软件和网络应用软件等。

4．简述TCP协议的工作流程。

答：在源主机上，应用层将一串应用数据流传送给传输层。

传输层将应用层的数据流截成分组，并加上TCP报头形成TCP段，送交网络层。

在网络层给TCP段加上包括源、目的主机IP地址的IP报头，生成一个IP数据包，并将IP数据包送交链路层。

链路层在其MAC帧的数据部分装上IP数据包，再加上源、目的主机的MAC地址和帧头，并根据其目的MAC地址，将MAC帧发往目的主机或IP路由器。

在目的主机，链路层将MAC帧的帧头去掉，并将IP数据包送交网络层。

网络层检查IP报头，如果报头中校验和与计算结果不一致，则丢弃该IP数据包；若校验和与计算结果一致，则去掉IP报头，将TCP段送交传输层。

传输层检查顺序号，判断是否是正确的TCP分组，然后检查TCP报头数据。若正确，则向源主机发确认信息；若不正确或丢包，则向源主机要求重发信息。

在目的主机，传输层去掉TCP报头，将排好顺序的分组组成应用数据流送给应用程序。这样目的主机接收到的来自源主机的字节流，就像是直接接收来自源主机的字节流一样。

5．串行通信和并行通信各有哪些特点？

答：在数据通讯中，若将要传送的每个字节的二进制代码按照由低位到高位的顺序，依次发送，这种传输数据的方式称为串行通信。由于计算机内部总线上传输的是并行数据，因此要和外部设备进行串行通讯时，在发送端要将并行数据转换成串行数据，在接收端再将串行数据转换成并行数据。

在数据通讯中，若将表示一个字节的8位二进制代码通过8条并行的通信信道由发送端同时发送出去，在接收端同时接受8位二进制代码，这种传输数据的方式称为并行通信。在远程通信中，同样传输速率的情况下，并行通信在单位时间内所传送二进制位数是串行通信的n

篇三：北京电大纺织分校-本科统考网考大学英语B必备-阅读理解教师版本

2009年4月收集的真题

阅读理解

Passage One

When weather is hot, you go to a lake or an ocean. When you are near a lake or an ocean, you feel cool. Why? The sun makes the earth hot, but it cannot make the weather very hot. Although, the air over the earth becomes hot, the air over the water stays cool. The hot air over the earth rises.

Then the cool air over the water moves in and takes the place of the hot air. When you are near a lake or an ocean, you feel the cool air when it moves in .You feel the wind, and the wind makes you feel cool.

Of course, scientists cannot answer all of our questions. If we ask, “Why is the ocean full of salt?” scientists will say that the salt comes form rocks. When a rock gets very hot or very cold, it cracks. Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. But then we ask, “What happens to the salt in the ocean? The ocean does not get more salty every year.” Scientists are not sure about the answer o this question.

We know a lot about our world. But there are still many answers that we do not have, and we are curious.

6. The main idea of the passage is ____________.

A. people feel cool when they are near a lake or an ocean

B. scientists can explain everything we want to know

C. scientists can explain many things except one thing

D. the salt in the ocean comes from rocks

7. You feel cool when you are near a lake or an ocean because ________.

A. the water is not so hot as the earth.

B. the earth is hot

C. the water is colder than the earth

D. cool air from the water moves towards the land

8. Now scientists know _______.

A. what makes people feel cool near a lake or an ocean in summer

B. everything about the ocean

C. why the ocean does not get more and more salty

D. what happens to the salt in the ocean

9. A rock cracks when _________.

A. rain fallsB. it gets very hot C. it gets very cold D. either B or C

10. People are always curious about the world around them because ___________.

A. they know nothing about itB. they know little about it

C. there are answers they do not haveD. there are a lot of interesting stories about it

Passage Two

If you do not use your arms or your legs for some time, they will become weak, when you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory works in the same way.

When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory is poor, he really means that he does not give it enough chance to become strong.

If a friend says that his arms and legs are weak, we know it is his own fault. But if he tells us that he has a poor memory, many of us think that his parent may be blamed, and few of us know that it is just his own fault. Have you ever found that some people can’t read or write but usually they have better memories? This is because they cannot read or write and they have to remember thing, they cannot write them down in a small notebook. They have to remember days, names songs and stories, so their memory is the whole time being exercises.

So if you want to have a good memory, learn from people ; practices remembering things in a way as other people do.

6. Someone can’t have a good memory if ________.

A. he can’t read or writeB. he doesn’t use his memory

C. his parents haven’t a good memory D. he doesn’t use his arms or legs for some time

7. If you do not use your arms or your legs for some time, _________________.

A. they become weak forever.

B. they are always strong.

C. they become weak but they slowly become strong again

D. they become weak and won’t become strong until you use them again.

8. Which of the following is true?

A. The way that your memory works is different from that of your arms or legs.

B. Your memory becomes weak if you do not give it enough chance for practice.

C. Don’t learn how to read and write if you want to have a better memory.

D. A good memory comes from less practice.

9. Few people know that it is only ______ if a friend has a poor memory.

A. his own faultB. his parent’s fault

C. his teacher’s fault D. his grandmothers’ fault

10. The writer wants to tell us ___________.

A. how to use our arms or legs B. how to have strong arms

C. how to have a good memoryD. how to learn from the people

Passage Three

A million tourists go to Barcelona every year. They want to see Antonio Gaude’s church. This unusual church has a strange history. Gaude was born in Spain in 1852. He had to work and study at the same time. He often missed classes because he had to work, but one day he designed a very unusual show-case for an exhibition in Paris. People began to give him work. He designed houses, offices and gardens. They were all very unusual. He was soon rich and famous. Then a rich bookseller said, “Will you build a church for the poor people of Barcelona? I will pay. I will build schools and workshops, too. They will help the people.” “I will do it,” said Gaudi. He

worked for forty years, but he could not finish the church. It was too big. He needed $10,000,000. He gave all his money to the church. He was poor again when he died in 1926, and only the front of the church was finished. But architects, engineers and tourists from all over the world come to see it. It is very strange, very modern and very revolutionary.

6. Which of the following titles best fits the passage?

A. Barcelona----- a Famous City B. A Strange History of an Unusual Church

C. A Poor Architect’s Unusual Works D. Antonio Gaudi’s Life

7. Which of the following is NOT true?

A. Gaudi was a Spanish architect.

B. Gaudi devoted most of his life to the building of the church.

C. People all over the world admire the architect very much.

D. Many tourists go to see Gaudi’s unfinished church.

8. Gaudi sometimes missed classes because ____________.

A. he didn’t like it B. he had to work at the same time

C. they were too difficult D. he had to build a church

9. The church is unusual because ______________.

A. it’s unfinished B. it’s strange

C. it’s modern D. all of the above

10. According to the passage, Gaudi ____________.

A. suffered a lot in his life B. was full of sympathy to the poor

C. always created unusual works D. both B and C

Passage Four

What must you do when you receive a present for your birthday? You have to sit down and write a thank-you note. The words “Thank you” are very important. We have to use them on so many occasions. We say them when someone gives us a drink, helps us to pick up things, hands us a letter, lends us book or gives us a gift.

Another important word is “please”. Many people forget to use it. It is rude to ask someone to do something without saying “please”. We have to use it when we ask for something, too. It may be a book or a pencil, more rice or more sauce, help or advice. It may be in the classroom , at home, at the bus-stop or over the counter. We have to use “please” to make our request pleasant.

We have to learn to say “sorry” too. When we have hurt someone’s feeling, we will have to go up and say we are sorry. When we have told a lie and feel sorry, we will have to use the same word. When we have forgotten something or broken a promise, we will have to explain with that word, too. “Sorry” is a healing word. We can make people forget wrongs by using it sincerely.

These three words are simple but important. They are pleasing words to use in any language.

6. When we receive a birthday present, we have to ___________.

A. return it B. give it to one of our friends

C. do nothing D. write a thank-you note

7. When someone helps us to do something, we should ____________.

A. thank him B. say “sorry” to him

C. use the word “please” D. not say anything

8. One of the important words in any language is __________.

A. “hello” B. “yes” C. “no” D. “please”

9. We have to use the word “please” when we ___________.

A. hurt someone’s feelingB. ask for something

C. forget something D. break a promise

10. The three important words in any language are __________.

A. “ thanks”, “ hello” and “goodbye” B. “yes” , “no” and “really”

C. “thanks”, “please” and “sorry” D. “well”, “please” and “pardon”

Passage Five

Mr. Perkin stood at the bus-stop and watched the cars go by. Many of the cars were new Beta 400s, and most of them were yellow. Mr. Perkin always were the same clothes as other men, ate the same food as other people , and did the same things after work, and at the end of the week, Mr. Perkin did not like to be different.

The following week, Mr Perkin bought a new, bright yellow Beta400s. He was satisfied with it, and drove to work in it the very next day. He was even more satisfied with his new car, when he saw all the other Beta 400s, in front , behind and on both sides of him.

Mr. Perkin parked his car in a big car-park near his office, and walked the rest of the way. But when he came back at five o’clock, there were so many bright yellow Beta 400s in the car-park that he did not know which car was his. He tried his key in some of the cars, but people passing by gave him a look he didn’t like. So he stopped.

Poor Mr. Perkin had to wait nearly two hours until his was the only yellow Beta 400s in the car-park.

6. Mr. Perkin wanted a new yellow Beta 400s because ________.

A. the bus did not comeB. he liked new clothes, food and cars

C. he liked to do the same as other people D. he liked to be different from others

7. He drove to work in his new car ________.

A. the very next day B. the day he bought it

C. a week he bought itD. on the day he first watched the cars passing

8. He was satisfied with his new car because ____________.

A．no one else had a yellow one B. it was the same as other cars all around him

C. he was in front of all the other cars D. other cars were not as bright as his

9. People gave him a look because ____________.

A. he had a nice new car B. he could not open the door of his car

C. he was in the wrong car-park D. he was trying to open more than one car

10. Mr. Perkin had to wait until ________.

A. there was only one yellow Beta 400s in the car-park

B. there was only one car in the car-park

C. there were no bright yellow cars in the car-park

D. there was no one about to look at him

Passage Six:

I am going to tell you a story about two drivers who wanted to park their cars in the same parking space.

The man who arrived at the parking space first was rather old with gray hair. He was driving a large Rolls Royce. The beautiful car stopped just in front of the parking space. Then the driver turned his head and very slowly began to reverse his car into the space.

Just as he was doing this, a young man in a Mini came up from behind. He noticed the space and drove straight in, nose first. The older driver in the Rolls Royce stopped his car suddenly. He was very angry and red in the face. He wound down his window and looked at the young man. But the young man wasn’t sorry. He had got out his car now and he was laughing. “You have to be young to do that!” he said to the older driver and pointed at the Mini and at the space he had just taken.

The older man said nothing. He just began to reverse his Rolls Royce again and crashed into the Mini very hard. There was not much of the Mini left when the older driver had finished. The young man watched what was happening and couldn’t believe his eyes. He was angry and very red in the face. The older driver looked out of the window and smiled. “You have to be rich to do that.” He said.

6. What is the story about?

A. Two drivers happened to crash into each other in a parking space.

B. Two cars crashed into each other due to the drivers’ dispute over a parking space.

C. One driver tried to park their cars in one small parking space.

D. The parking space was too small to hold two cars at the same time.

7. What do you know about the two drivers?

A. The young driver was quicker than the older driver.

B. Each of them had an expensive car.

C. They didn’t see each other while they were getting into the same parking space.

D. Both of them were good at driving.

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