云南大学网络课作业英语二答案

云南大学网络课作业英语二答案篇一

云大成教学院大学英语(一)网络课程答案

云南大学网络课作业英语二答案篇二

云南大学成教大学英语(二)A答案

云南大学网络课作业英语二答案篇三

大学英语(1)第二次网络作业和答案

大学英语（1）第二次网络作业

(三次网络作业的平均成绩占期末考试成绩30%，请大家在认真复习好《大学英语》课本第一册第3-4单元的课文、词汇与短语后完成如下作业；作业一经批改评分，将不能修改；此次作业完成后应交到“在线作业”一栏本次作业界面中；作业必须按最后一页答卷表格格式作答，不要以附件形式缴交)

一. 阅读：

（ 1 ）

The angry woman stood by the station. “ The railway owes me £12,”she said to Harry Jenks, the booking clerk (订票员). “My ticket was for May 22nd, and there was no ship from Jersey that night. My daughter and I had to stay in a hotel. It cost me £12.”

Harry was worried. He remembered selling the woman a return ticket. “ Come into the office, madam,” he said, “ I’ll just check the Jersey timetable for May 22nd .”

The woman and her little girl followed him inside. She was quite right, as Harry soon discovered. There was no sailing on May 22nd. How ever had he made such a big mistake? Wondering what to do, he smiled at the child. “You look healthy,” he said to her. “ Did you have a nice holiday in Jersey?” “ Yes,” she answered. “ The beach was beautiful. And I can swim too!”

“ That’s fine,” said Harry. “ My little girl can’t swim a bit yet. Of course, she’s only three-----”

“ I’m four,” the child said proudly. “ I’ll soon be four and a half.”

Harry turned to the mother. “ I remember your ticket, madam,” he said. “ But you didn’t get one for your daughter, did you?”

“ Er, well-----” The woman looked at the child. “ I mean-----she hasn’t started school yet. She’s only four.” “ A four year old child must have a ticket, madam. A child’s

return to Jersey costs----let me see----£13.50. So if the railway pays your hotel bill, you will owe £1.50.The law is the law, but since we have made a mistake-----”

The woman stood up, took the child’s hand and left the office.

1. The angry woman went to the station __________.

a. to ask the railway to pay her hotel bill

b. to buy a ticket for her daughter

c. to have a friendly talk with the booking clerk

d. to buy the Jersey timetable

2. Harry had a talk with the girl in order to _________.

a. find out how old the girl was and whether the girl had been to Jersey

b. please the girl and her mother

c. get some information about Jersey

d. find out how many days they spent in Jersey

3. The hotel bill is __________.

a. more than the cost of a child’s ticket

b. exactly the same as the cost of a child’s ticket c. less than the cost a child’s ticket

d. more than the cost of a woman’s ticket

4. The child is ___________ years old.

a. two b. four c. three d. five

5. A girl of _________ should buy a ticket according to the law of the railway.

a. three b. four c. five d. six

( 2 )

In the eighteen century young ladies in Italy were taught reading, writing, music and arithmetic(算术). But their knowledge of history and geography(地理) was very poor.

Once the French ambassador (大使) in Rome was giving a ball

(舞会) to which many important people were invited. The Italian Minister of Foreign Affairs(外交部长) came very late. A young lady, who was well acquainted with him, saw him enter the ball-room(舞厅) and asked why he was so late.

“You see,” said the Minister, “there has been a little accident at the King’s palace.”

The curious young lady asked the Minister to tell her what had happened at the King’s palace.

“Oh, nothing important,” answered the Minister. “The ambassador of Brail (巴西), who was to be presented to the King, forgot to take his credentials(外交使节所递的国书) with him and was obliged to go back to his hotel to bring them. If he had left them in Brail we should have had to wait at least six months for them.”

“Is Brail so far from Rome?” asked the lady, who knew very little geography.

“It is in the New World,” said the Minister.

“In the New World?” repeated the lady in great astonishment.

“Yes, in the New World,” answered the Minister in a sarcastic(讽刺的) tone, “which was discovered by Christopher Columbus(哥伦布).”

When the young lady heard this, she rushed into the middle of the ball-room and shouted as loud as she could:

“Ladies and gentlemen, have you heard the latest news? A new world has just been discovered by a certain Christopher Columbus.”

6． The Italian foreign minister came to the hall very late

because ________.

a. someone was hurt in the King’s palace

b. he had had something to do at home

c. he was reluctant to come to the hall

d. he was delayed by a little accident

7. What happened at the King’s palace?

a. The ambassador left his credentials in Brail.

b. The King was late; the Brazilian ambassador had to wait for him.

c. For some reason the ambassador had to go back to Brail. d. The Brazilian ambassador forgot to take his credentials with him.

8. Where did the ambassador leave his credentials?

a. In his office

b. In Rome

c. In the hotel

d. In Brail

9. The reason why the young lady shouted her announcement was

that ________.

a. she was the hostess of the ball

b. she was well acquainted with the Minister

c. she had never heard about Columbus

d. she wanted to broadcast the surprising news

10. Her announcement showed she was ________________.

a. clever

b. thoughtless

c. knowledgeable

d. ignorant

二．介词填空： （按课本课文内容填入适当的介词）

11．If you don’t, you could end ____ spending hundreds of

dollars more than you should have.

12. As activities are usually carried _____ during one’s{云南大学网络课作业英语二答案}.

spare time, leisure has the following functions: relaxation, recreation and entertainment, and personal development.

13. You should start packing ____least a week in advance.

14. Because you don’t want to stay _____ all night packing

and wear yourself out before you even leave for the trip.

15. Moreover, you should also find ____ the best time of year

to go.{云南大学网络课作业英语二答案}.

（提示：答案必须填入下面的答卷表格内，只要复制粘贴提交答卷即可，请不要用附件形式提交）

大学英语（1）第二次网络作业答卷纸

姓名： 学号：

专业： 所在教学中心：

云南大学网络课作业英语二答案篇四

自考英语二三七作业及答案

山东省高等教育自学考试

英语（二）模拟试题1

（课程代码：00015 考试时间：150分钟）

注意事项：

答案必须写在答题卡规定的区域内，未按要求作答的答案无效。

I. Vocabulary and Structure (10 points, 1 point for each item)

在每小题列出的四个备选项中只有一个是符合题目要求的，请将其选出并将答题卡的相应代码涂黑。错涂、多涂或未涂均无分。

1. Only by developing an understanding and tolerance of different cultural values reach the goal of communicating with native English speakers.(C )

A. a Chinese English learner can B. does a Chinese English learner

C. can a Chinese English learner D. a Chinese English learner did

2. ___A___ the leadership of the party, we could not live happily today.

A. But for B. In case

C. As for D. Because of

3. I have no idea that this party is __B_____.

A. in her face B. in her honor

C. in her way D. for her fancy

4. There is no ___B___ in asking him, for he knows nothing about it.

A. way B. point

C. sense D. meaning

5. I ____A__ leave my house when the phone rang.

A. was about to B. had to

C. was long to D. was way to

6. ____D___ I asked, I should tell the truth.

A. Was B. Am

C. Been D. Were

7. Try ____C__ you will, you can‟t succeed.

A. if B. how

C. as D. after

8. Suddenly the wild animal charged ___D_____ us.

A. into B. for

C. of D. at

9. His illness was __C____ to bad food.

A. because B. about

C. due D. thank

10. He identified her happiness ___A___ his own.

A. with B. in

C. for D. as

II. Cloze Test (10 points, 1 point for each item)

下列短文中有十个空白，每个空白有四个选项。请根据上下文要求选出最佳

答案，并将答题卡的相应代码涂黑。

The artist Andy Warhol famously said that he thought everybody would be famous for fifteen minutes, and with the increasing power of the internet, that‟s true today than ever. Anybody with an internet connection and a computer can now become a celebrity.

A celebrity is somebody who is only, or perhaps mostly famous through their presence the internet, an internet personality who crosses over to the mainstream. A web celebrity. A celebrity.

As people rely on the internet more and more is becoming increasingly attractive a platform for new writing, music, film, and art. The writer Stephen King has published books only on the internet and some musicians get a recording contract through the popularity they build on the web.

its paper copy and only publish online. As its audience grows, the internet is on the internet become incredibly space of time. This is sing a famous song can get them on TV shows and magazines. It‟s an age of celebrity!

11. A. more B. less C. much D. little

12. A. in B. on C. at D. to

13. A. as B. like C. of D. for

14. A. like B. in C.as D. to

15. A. down B. on C. up D. into

16. A. adopt B. adept C. discard D. abandon

17. A. posted B. advertised C. communicated D. comprehend

18. A. popular B. perilous C. fabulous D. fantastic

19. A. a time B. a period C. an age D. a stage

20. A. a presence B. an appearance C. an outlook D. an expression

III. Reading Comprehension (30 points, 2 points for each item)

从下列每篇短文的问题后所给的四个选项中选出一个最佳答案，并将答题卡的相应代码涂黑。

Passage One

Questions 21 to 25 are based on the following passage.

Gliese 581g is the sixth planet to be found circling a dwarf star some 20 light-years away, in the constellation of Libra. On paperit looks good – three times the mass of

the Earth with possibly a rocky surface and enough gravity to hold on to an atmosphere.

The researchers also promised shirt-sleeve weatherin some regions, but not everywhere. One side of the planet is almost always in sunshine; the other almost always in darkness and estimated temperatures range from minus four degrees Celsius to a very hot 71 degrees. A year meanwhile would go by in just 37 days.

Of course, whether life could really be supported on Gliese 581g will need much more investigation and, most probably, technologies which don't exist yet. But the astronomers say planet hunting is getting easier and they were surprised how quickly they detected the tell-tale signsof this distant body, using ground-based telescopes.

21. Which of the following is correct about Gliese 581g?(B)

A. It is a dwarf star with gravity.

B. It is a planet like the earth.

C. It was discovered many centuries ago.

D. It is very close to the earth.

22. What does Gliese 581g look like?(D)

A. It has the mass of the sun.

B. It has about the same mass as the earth and its atmosphere.

C. Its rock and atmosphere are about three times the mass of the earth.

D. It is heavier than the earth and has a rocky surface.

23. Which of the following is correct about the gravity of Gliese 581g?(C)

A. It fixes the mass on.

B. It is too small to keep anything on the ground.

C. It is enough to hold on to an atmosphere.

D. It helps Gliese 581g to balance between the earth and the sun.

24. What does shirt-sleeve weatherprobably mean?(A)

A. So warm that a jacket is not needed.

B. Changeable.

C. Cold.

D. Extremely cold.

25. How was Gliese 581g found?(C)

A. A scientist discovered it on the way to the moon.

B. Some scientists found it with a telescope on the shuttle.

C. It was found using telescopes on the earth.

D. It was found with the help of a computer.

Passage Two

Questions 26 to 30 are based on the following passage.

Officially almost 60,000 Nepalese women are now working in the Middle East but the unofficial estimate is closer to 200,000. Many of them are under 30 years old and will be directly affected by the new ban.

The government's been under growing pressure to do more to protect its workers. Women employed in the informal sector as part of a household are very vulnerable. Nepal's Embassies in the region say they deal with numerous cases of alleged physical or sexual abuse, as well as complaints about unpaid wages and terrible conditions. Many run safe houses to support women who flee their employer's homes. It's only 18 months since the government ended a 12-year ban on all women workers to the Gulf. That wasimposed after a young woman working in Kuwait committed suicide. Now they're adopting this partial ban in the hope that older women might be less at risk. Nepal has a high unemployment rate and the government is trying to strike a balance between protection and allowing women to pursue opportunities. Other countries face the same dilemma. Two months ago, Kenya banned its citizens from working in the Middle East because, it said, increasing numbers were being mistreated. Last year, Indonesia introduced a ban on women working as maids in the region. That followed numerous cases of abuse and the execution of an Indonesian maid who was accused of killing her former employer.

26. Who will be most probably be affected by the new ban?(A)

A. Young Nepalese women working in the Middle East.

B. Nepalese women just back from the Middle East.

C. Nepalese women working at home.

D. Nepalese women who wants to work for rich families.

27. Why does the Nepalese government decide to adopt the ban?(C)

A. Because they wanted women to work at home.

B. Because they wanted Nepalese women to have equal opportunities.

C. Because they wanted to protect the Nepalese women.{云南大学网络课作业英语二答案}.

D. Because they had a bad relationship with the gulf countries.

28. How are the Nepalese women treated when working in the Middle East？(D)

A. They are well treated.

B. They are offered many opportunities.

C. They have much freedom.

D. Many of them are mistreated and abused.{云南大学网络课作业英语二答案}.

29. Which of the following is correct about the ban?(B)

A. It is historical and has never been imposed before.

B. A year and a half ago, another ban existed.

C. It has lasted twelve years.

D. It solves the unemployment problem at home.

30. Which of the following is correct?(C)

A. Middle East women work outside their countries.

B. Women working in the Middle East all come from Asia.

C. Women working in the Middle East need protection.

D. Embassies cannot do anything to protect women from their country.

Passage Three

Questions 31 to 35 are based on the following passage.

Aslick advert by the Melbourne tourist board shows pictures of itsenviable schools, beaches, transport system and nightlife, all of which have helped it earn the number one spot as the world's most liveable city.

The 140 cities in the survey are judged on five broad categories:stability, healthcare, culture and environment, education and infrastructure. The top scorers tend to be mid-sized cities in wealthy countries with a low population density. Some seven of the top ten – including Vancouver, Toronto and Sydney – are in Australia or Canada. Vienna, Helsinki and Auckland also made the top ten.

Of the cities surveyed – and some like Kabul and Baghdad were not included for safety reasons – Dhaka in Bangladesh was rated the least liveable. Lagos, Harare, Algiers and Karachi all scored poorly as well.

The city that has dropped fastest down the list in the last year is Damascus, due to the ongoing conflict in Syria, while infrastructure improvements in China mean that cities like Shanghai and Suzhou have scored better than they did last year.

31. Which of the following cities are not surveyed for liveability?(C)

A. Damascus

云南大学网络课作业英语二答案篇五

计算机网络课后作业以及答案(中英文对照)

Chapter1

1-11.What are two reasons for using layered protocols?

(请说出使用分层协议的两个理由)

答：通过协议分层可以把设计问题划分成较小的易于处理的片段。分层意味着某一层的协议的改变不会影响高层或低层的协议。

1-13. What is the principal difference between connectionless communication and connection-oriented communication?

(在无连接通信和面向连接的通信两者之间，最主要的区别是什么？) 答：主要的区别有两条。

其一：面向连接通信分为三个阶段，第一是建立连接，在此阶段，发出一个建立连接的请求。只有在连接成功建立之后，才能开始数据传输，这是第二阶段。接着，当数据传输完毕，必须释放连接。而无连接通信没有这么多阶段，它直接进行数据传输。

其二：面向连接的通信具有数据的保序性， 而无连接的通信不能保证接收数据的顺序与发送数据的顺序一致。

1-20. A system has an n-layer protocol hierarchy. Applications generate messages of length M bytes. At each of the layers, an h-byte header is added. What fraction of the network bandwidth is filled with headers? (一个系统有n层协议的层次结构。应用程序产生的消息的长度为M字节。在每一层上需要加上一个h字节的头。请问，这些头需要占用多少比例的网络带宽)

答：hn/(hn+m)*100%

1-28. An image is 1024 x 768 pixels with 3 bytes/pixel. Assume the image is uncompressed. How long does it take to transmit it over a 56-kbps modem channel? Over a 1-Mbps cable modem? Over a 10-Mbps Ethernet? Over 100-Mbps Ethernet?

(一幅图像的分辨率为1024 x 768像素，每个像素用3字节来表示。假设该图像没有被压缩。请问，通过56kbps的调制解调器信道来传输这幅图像需要多长时间？通过1Mbps的电缆调制解调器呢？通过10Mbps的以太网呢？通过100Mbps的以太网呢?)

答：The image is 1024*768*3 bytes or 2359296 bytes.This is 18874368 bit. At 56,000 bits/sec, it takes about 337.042 sec. At 1,000,000 bits/sec, it takes about 18.874 sec. At 10,000,000 bits/sec, it takes about 1.887 sec. At 100,000,000 bits/sec, it takes about 0.189 sec.

Chapter2

2-2. A noiseless 4-kHz channel is sampled every 1 msec. What is the maximum data rate?

(一条无噪声4kHz信道按照每1ms一次进行采样，请问最大数据传输率是多少？)

答：无噪声信道最大数据传输率公式：最大数据传输率=2Hlog2V b/s。因此最大数据传输率决定于每次采样所产生的比特数，如果每次采样产生16bits，那么数据传输率可达128kbps；如果每次采样产生1024bits，那么可达8.2Mbps。注意这是对无噪声信道而言的，实际信道总是有噪声的，其最大数据传输率由香农定律给出。

2-4. If a binary signal is sent over a 3-kHz channel whose signal-to-noise ratio is 20 dB, what is the maximum achievable data rate?

(如果在一条3kHz的信道上发送一个二进制信号，该信道的信噪比为20dB，则最大可达到的数据传输率为多少？)

答：信噪比为20 dB 即 S/N =100由于 log2101≈6.658，由香农定理，该信道

的信道容量为3log2(1+100)=19.98kbps。

又根据乃奎斯特定理，发送二进制信号的3kHz 信道的最大数据传输速率为 2*3*log22=6kbps。

所以可以取得的最大数据传输速率为6kbps。

2-5. What signal-to-noise ratio is needed to put a T1 carrier on a 50-kHz line?

(在50kHz的线路上使用1T线路需要多大的信噪比？)

答：为发送T1 信号，我们需要

所以，在50kHz 线路上使用T1 载波需要93dB 的信噪比。

2-34. A signal is transmitted digitally over a 4-kHz noiseless channel with one sample every 125 µsec. How many bits per second are actually sent for each of these encoding methods?

(a) CCITT 2.048 Mbps standard.

(b) DPCM with a 4-bit relative signal value.

(c) Delta modulation.

（一个信号在4kHz的无噪声信道上以数字方式进行传输，没125us采样一次。请问，按照以下的编码方法，每秒钟实际发送多少位？

（a）CCITT 2.048Mbps标准。

（b）有4位相对信号值的DPCM。

（c）增量调制。

）

答：a．CCITT 2.048Mbps 标准用32 个8 位数据样本组成一个125的基本帧，30 个信道用于传信息，2 个信道用于传控制信号。在每一个4kHz

信道上发送

的数据率就是

8*8000=64kbps。

b．差分脉码调制（DPCM）是一种压缩传输信息量的方法，它发送的不是每一次抽样的二进制编码值，而是两次抽样的差值的二进制编码。现在相对差值是4 位，所以对应每个4kHz 信道实际发送的比特速率为4*8000=32bps。

c．增量调制的基本思想是：当抽样时间间隔s t 很短时，模拟数据在两次抽样之间的变化很小，可以选择一个合适的量化值作为阶距。把两次抽样的差别近似为不是增加一个就是减少一个。这样只需用1bit 二进制信息就可以表示一次抽样结果，而不会引入很大误差。因此，此时对应每个4kHz 信道实际发送的数据速率为1*8000=8kHz。

2-43. Suppose that x bits of user data are to be transmitted over a k-hop path in a packet-switched network as a series of packets, each containing p data bits and h header bits,with x >> p+h.The bit rate of the lines is b bps and the propagation delay is negligible.What value of p minimizes the total delay?

(假定x位用户数据将以一系列分组形式，在一个分组交换网络中沿着一条共有k跳的路径向前传播，每个分组包含p位数据和h位的头，这里x>>p+h。线路的传输率为b bps，传播延迟忽略不计。请问，什么样的p值使总延迟最小？) 答：所需要的分组总数是x /p ，因此总的数据加上头信息交通量为(p+h)*x/p位。 源端发送这些位需要时间为(p+h)*x/pb

中间的路由器重传最后一个分组所花的总时间为(k-1)*(p+h)/ b

因此我们得到的总的延迟为

对该函数求p 的导数，得到

令

得到

因为p＞0，所以

故

时能使总的延迟最小。

2-53. A CDMA receiver gets the following chips: (-1 +1 -3 +1 -1 -3 +1 +1). Assuming the chip sequences defined in Fig. 2-45(b), which stations transmitted, and which bits did each one send?

(一个CDMA接收器得到了下面的时间片：(-1 +1 -3 +1 -1 -3 +1 +1)。假设时间片序列如图2.45（b）中所定义，请问哪些移动站传输了数据？每个站发送了什么位?)

答：Just compute the four normalized inner products:

（1+1 3+1 1 3+1+1）d（1 1 1+1+1 1+1+1）/8=1

（1+1 3+1 1 3+1+1）d（1 1+1 1+1+1+1 1）/8=1

（1+1 3+1 1 3+1+1）d（1+1 1+1+1+1 1 1）/8=0

（1+1 3+1 1 3+1+1）d（1+1 1 1 1 1+1 1）/8=1

The result is that A and D sent 1 bits, B sent a 0 bit, and C was silent.

Chapter3

3-3.The following data fragment occurs in the middle of a data stream for which the byte-stuffing algorithm described in the text is used: A B ESC

C ESC FLAG FLAG D. What is the output after stuffing?

(数据片断（A B ESC C ESC FLAG FLAG D）出现在一个数据流的中间，而成帧方式采用的是本章介绍的字节填充算法，请问经过填充之后的输出时什么？) 答：After stuffing, we get A B ESC ESC C ESC ESC ESC FLAG ESC FLAG D.

3-15. A bit stream 10011101 is transmitted using the standard CRC method described in the text. The generator polynomial is x3 + 1. Show the actual bit string transmitted. Suppose the third bit from the left is inverted during transmission. Show that this error is detected at the receiver's end.

(利用本章中介绍的标准多项式CRC方法来传输位流1001101。生成器多项式为x3+1。请给出实际被传输的位串。假设在传输过程中左边第三位变反了。请证明，这个错误可以在接收端被检测出来。)

答：The frame is 10011101. The generator is 1001. The message after appending three zeros is 10011101000. The remainder on dividing 10011101000 by 1001 is 100. So, the actual bit string

Transmitted is 10011101100. The received bit stream with an error in the third bit from the left is 10111101100.Dividing this by 1001 produces a remainder 100, which is different from zero. Thus, the receiver detects the error and can ask for a retransmission.

3-18. A 3000-km-long T1 trunk is used to transmit 64-byte frames using protocol 5. If the propagation speed is 6 µsec/km, how many bits should the sequence numbers be?

(一条3000公里长的T1骨干线路被用来传输64字节的帧，两端使用了协议

5。如果传输速度为6us/公里，则序列号应该有多少位？)

答：为了有效运行，序列空间（实际上就是发送窗口大小）必须足够的大，以允许发送方在收到第一个确认应答之前可以不断发送。信号在线路上的传播时间为 6×3000=18000us，即18ms。 在T1 速率，发送64 字节的数据帧需花的时间：64×8÷(1.536×106)= 0.33us。 所以，发送的第一帧从开始发送起，18.33ms 后完全到达接收方。确认应答又花了很少的发送时间（忽略不计）和回程的18ms。这样，加在一起的时间是36.33ms。发送方应该 有足够大的窗口，从而能够连续发送36.33ms。 36. 33/0.33=110 也就是说，为充满线路管道，需要至少110 帧，因此序列号为7 位。

3-22. In protocol 6, when a data frame arrives, a check is made to see if the sequence number differs from the one expected and no_nak is true. If both conditions hold, a NAK is sent. Otherwise, the auxiliary timer is started. Suppose that the else clause were omitted. Would this change affect the protocol's correctness?

(在协议6中，当一个数据帧到达的时候，需要执行一个检查，看它的序列号是否与期望的序列号不同，并且no_nak为真。如果这两个条件都成立，则发送一个NAK。否则的话，启用辅助定时器。假定else子句被省略掉。这种改变会影响协议的正确性吗？)

答：可能导致死锁。假定有一组帧正确到达，并被接收。然后，接收方会向前移动窗口。

现在假定所有的确认帧都丢失了，发送方最终会产生超时事件，并且再次发送第一帧，接收方将发送一个NAK。然后NONAK 被置成伪。假定NAK 也丢失了。那么从这个时候开始，发送方会不断发送已经被接收方接受了的帧。接收方只是忽略这些帧，但由于NONAK 为伪，所以不会再发送NAK，从而产生死锁。如果设置辅助计数器（实现“else”子句），超时后重发NAK，终究会使双方重新获得同步。

3-31. Consider an error-free 64-kbps satellite channel used to send 512-byte data frames in one direction, with very short acknowledgements coming back the other way. What is the maximum throughput for window sizes of 1, 7, 15, and 127? The earth-satellite propagation time is 270 msec. （考虑在一个无错误的64kbps卫星信道上单向发送512字节的数据帧，有一些非常短的确认从另一个方向回来。对于窗口大小为1、7、15、和27的情形，最大的吞吐量分别是多少？从地球到卫星的传输时间为270ms。）

答：使用卫星信道端到端的传输延迟为270ms，以64kb/s 发送，周期等于604ms。发送一帧的时间为64ms，我们需要604/64=9 个帧才能保持通道不空。 对于窗口值1，每604ms 发送4096 位，吞吐率为4096/0.604=6.8kb/s。

对于窗口值7，每604ms 发送4096*7 位，吞吐率为4096*7/0.604=47.5kb/s。 对于窗口值超过9（包括15、127），吞吐率达到最大值，即64kb/s。

云南大学网络课作业英语二答案篇六

云南大学网络课多媒体技术基础作业 - 2

★单选题：>

下面（ ）不是常用的音频文件的后缀。

A、WAV

B、MOD

C、MP3

D、DOC

★单选题：>

位图与矢量图比较，可以看出（ ）。

A、位图比矢量图占用空间更少

B、对于复杂图形，位图比矢量图处理得更快

C、位图与矢量图占用空间相同

D、对于复杂图形，位图比矢量图处理得更慢

★单选题：>

我国电视系统采用的制式是PAL-D，其彩色空间是（ ）。

A、RGB

B、HIS

C、YUV

D、YIQ

以上答案提交后有误

★单选题：>

MIDI文件比较小，因为它记录的是（ ）。

A、音符及事件序列

B、波形

C、音频帧

D、采样数据

★单选题：>

关于图像数字化，以下说法错误的是（ ）

A、数字化的图像不能直接观看，必须借助播放设备及软件才能观看。

B、数字化的图像不会失真。

C、数字图像传输非常方便。

D、图像数字化就是将图像用0、1编码的形式来表示。

★单选题：>

以下( ）是音频格式文件。

A、JPG

B、MID

C、GIF

D、BMP

★单选题：>{云南大学网络课作业英语二答案}.

以下( ）不是音频格式文件。

A、RM

B、MIDI

C、WMA

D、SWF

★单选题：>

MIDI是（ ）。

A、一种音乐编码格式

B、是乐器数字接口

C、是模拟音乐

D、是压缩格式音乐

★单选题：>

以下是视频文件格式的为（ ）。

A、GIF

B、JPG

C、AVI

D、MP3

★单选题：>

以下（ ）是Windows的通用声音格式。

A、WAV

B、MP3

C、BMP

D、CAD

★多选题：>

下列说法是正确的是（ ）。

A、图像都是由一些排成行列的点（像素）组成的，通常称为位图或点阵图。

B、图形是用计算机绘制的画面，也称矢量图。

C、图像的最大优点是容易进行移动、缩放、旋转和扭曲等变换。

D、图形文件中只记录生成图的算法和图上的某些特征点，数据量较小。

★多选题：>

以下文件类型中，（ ）是音频格式。

A、.WAV

B、.MP3

C、.BMP

D、.JPG

★多选题：>

下列方法中，可以从（ ）中获得数字音频素材。

A、用磁带录音机

B、用Windows中的CD播放器录音

C、从CD-ROM音频库中获取MIDI音乐

D、用MIDI作曲软件制作MIDI音乐

★多选题：>

以下关于视频文件格式的说法正确的是( )。

A、RM文件是RealNetworks 公司开发的流式视频文件

B、MPEG文件格式是运动图像压缩算法的国际标准格式

C、MOV文件不是视频文件

D、AVI文件是Microsoft公司开发的一种数字音频与视频文件格式

★多选题：>

下面关于视频质量、数据量、压缩比的关系的论述，( )是正确的。

A、视频质量越高数据量越大

B、随着压缩比的增大解压后视频质量开始下降

C、压缩比越大数据量越小

D、数据量与压缩比是一对矛盾

以上答案提交后有误

★多选题：>