题目内容（请给出正确答案）

[主观题]

II. Concepts: B1-7 （5 points each, 35 points in to...

II. Concepts: B1-7 (5 points each, 35 points in total) B1. What is the main task of the internet layer in the TCP/IP reference model respectively？ What kind of protocol performs that task？ B2. Please explain the differences between switches and routers. Hint you: Which layer do they work at？ What kind of address do they forward data based on？ B3. Why we need media access control？ Please list two or more media access control methods. B4. What is the exposed station problem？ Please sketch a graph to explain if necessary. B5. Besides flooding, what other routing algorithms have you learned？ B6. Transport layer uses both flow control and congestion control. Please tell us what flow control is and what congestion control is？ B7. What is the main difference between TCP and UDP？

暂无答案

如搜索结果不匹配，请联系老师获取答案

您可能会需要：

重置密码查看订单联系客服

安装上学吧APP，拍照搜题省时又省心！

更多“II. Concepts: B1-7 （5 points e…”相关的问题

第1题

So you've got an invention — you and around 39,000 others each year, according to 2002 statistics!

The 64,000-dollar question, if you have come up with a device which you believe to be the answer to the energy crisis or you've invented a lawnmower which cuts grass with a jet of water (not so daft, someone has invented one), is how to ensure you're the one to reap the rewards of your ingenuity. How will all you garden shed boffins out there keep others from capitalizing on your ideas and lining their pockets at your expense?

One of the first steps to protect your interest is to patent your invention. That can keep it out of the grasp of the pirates for at least the next 20 years. And for this reason inventors in their droves beat a constant trail from all over the country to the doors of an anonymous grey-fronted building just behind London's Holborn to try and patent their devices.

The building houses the Patent Office. It's an ant heap of corridors, offices and filing rooms—a sorting house and storage depot for one of the world's biggest and most varied collections of technical data. Some ten million patents — English and foreign — are listed there.

File after file, catalogue after catalogue detail the brain-children of inventors down the centuries, from a 1600's machine gun designed to fire square bullets at infidels and round ones at Christians, to present-day laser, nuclear and computer technology.

The first letters' patent were granted as long ago as 1449 to a Flemish craftsman by the name of John Utynam. The letters, written in Latin, are still on file at the office. They were granted by King Henry Ⅵ and entitled Utynam to import into this country his knowledge of making stained glass windows in order to install such windows at Eton College.

Present-day patents procedure is a more sophisticated affair than getting a go-ahead note from the monarch. These days the strict procedures governing whether you get a patent for your revolutionary mouse-trap or solar-powered back-scratcher have been reduced to a pretty exact science.

From start to finish it will take around two and a half years and cost ￡ 165 for the inventor to gain patent protection for his brainchild. That's if he's lucky. By no means all who apply to the Patent Office, which is a branch of the Department of Trade, get a patent.

A key man at the Patent Office is Bernard Partridge, Principal Examiner (Administration), who boils down to one word the vital ingredient any inventor needs before he can hope to overcome the many hurdles in the complex procedure of obtaining a patent — "ingenuity".

People take out a patent because they want to______.

A．keep their ideas from being stolen

B．reap the rewards of somebody else's ingenuity

C．visit the patent office building

D．come up with more new devices

点击查看答案

第2题

SECTION 1 (10 points)

Listen to the following passages and then decide whether the statements below are true or false. There are 10 questions in this section, with 1 points each. You will hear the recording only ONCE. At the end of the recording, you will have 2 minutes to finish this section.

听力原文： Let's face it -- we all have some form. of stress. Whether it's due to work, school reports, family, or relationships, we could all use a break now and then. Yet in the hustle and bustle of everyday life, a lot of us can't find the time to just drop everything and take it easy.

Well, what if someone told you that by just playing music from classical composers like Mozart or Strauss, you might find your job a little easier and that you might even be able to relax? This has actually been found to be true: listening to classical music has proven to be beneficial to learning and mind relaxation. It can also reduce our levels of stress.

Various studies of children have shown that those who receive music education or play a musical instrument often have increased academic skills. Don Campbell, author of The Mozart Effect, has dedicated himself to studying the effects of music on the mind and body. He counsels students that classical music playing in the background can help them concentrate for longer periods of time and memorize material more easily. He feels that Mozart's music has a balance that makes it especially beneficial. But Campbell doesn't stop with Mozart. He says that Bach can stimulate the mind, military marches can rev up the body, and religious music can help create a meditative mood. It's important to find what works best for your situation.

So the next time you feel yourself overwhelmed with work and deadlines, or if you're just finding it difficult to concentrate, remember the power of music.

A lot of people can't find the time to have a break.

A．正确

B．错误

点击查看答案

第3题

【B5】

A．relies on

B．lies in

C．based on

D．according to

点击查看答案

第4题

SECTION 1 (10 points)

听力原文： My story began in the years following World War Ⅱ, when men like my father who had served their country returned home to settle down, make a living and raise a family. It was the beginning of the Baby Boom, an optimistic time. The United States had saved the world from fascism, and now our nation was working to unite former adversaries in the aftermath of war, reaching out to allies and to former enemies, securing the peace and helping to rebuild a devastated Europe and Japan. Although the Cold War was beginning with the Soviet Union and Eastern Europe, my parents and their generation felt secure and hopeful. American supremacy was the result not just of military might, but of our values and of the abundant opportunities available to people like my parents who worked hard and took responsibility. Middle-class America was flush with emerging prosperity and all that comes with it—new houses, fine schools, neighborhood parks and safe communities. Yet our nation also had unfinished business in the post-war era, particularly regarding race. And it was the World War Ⅱ generation and their children who woke up the challenges of social injustice and inequality and to the ideal of extending America's promise to all of its citizens. My parents were typical of a generation who believed in the endless possibilities of America and whose values were rooted in the experience of living through the Great Depression.

My father served in World War II.

A．正确

B．错误

点击查看答案

第5题

Section A

Directions: This section is to test your ability to understand short dialogues. There are 5 recorded dialogues in it. After each dialogue, there is a recorded question. The dialogues and the questions will be spoken only once. When you hear a question, you should decide on the correct answer from the 4 choices A , B, C, and D.

听力原文：M: How much are these pens, please?

W: 2 for 7 dollars now. They used to be 5 dollars each.

Q: How much will the man have to pay if he buys 4 pens?

(1)

A．＄ 7.

B．＄ 10.

C．＄ 5.

D．＄ 14.

点击查看答案

第6题

Despite overwhelming scientific evidence that tobacco causes more than 400 000 deaths each year, our nations children continue to have easy access to cigarettes and spit tobacco. There are no significant restrictions on tobacco marketing that target teenagers, no national anti-smoking programs under way, and none on the drawing board. Despite all the research on the dangers of secondhand smoke, there are no nationwide protections against it. To top it all off, the United States has among the weakest package warnings and the lowest tobacco product prices in the industrialized nations of the world. Yet, we now have the opportunity to finally address the biggest and most preventable health problem facing this nation. After a long and thorough analysis, President Clinton has come forward with a statement of principles and direction for a national tobacco control plan that represents a major step.

点击查看答案

第7题

第二节完型填空

阅读下面短文，从短文后所给各题的四个选项(A、B、C和D)中选出能填入相应空白处的最佳选项。

Bringing Art into Hospitals

The medical world is gradually realizing that the quality of the 【B1】 in hospitals may play an important 【B2】 to help patients to get better.

As 【B3】 of nationwide effort in Britain to bring 【B4】 out 【B5】 the museums and into

【B6】 places, some of the country's best artists have 【B7】 in to change older hospital and to soften the 【B8】 edges of modem buildings. Of the 2500 national health service hospitals in Britain, almost 100 now have very valuable collections of present art in passages, waiting areas and treatment rooms.

These recent movements first 【B9】 by one artist, Peter Senior, who set up his studio at a Manchester hospital on northeastern England during the early 1970s. He felt the artist had lost his place in modem society, and 【B10】 he should be enjoyed by a wider audience.

A common hospital waiting room might have 【B11】 5 000 visitors each week, what a better place to hold regular exhibitions of art! Senior held the first exhibition of his own paintings in the out-patients waiting area of the Manchester Royal Hospital in 1975. Believed to be Britain's first hospital artist, Senior was so much 【B12】 that he was soon joined 【B13】 a team of six young art school graduates.

The effect is 【B14】 , now in the 【B15】 and waiting rooms the visitors 【B16】 a full view of fresh colors, playful images and restful countyards.

The quality of the environment may 【B17】 the need for expensive drags when a patient is 【B18】 from all illness. A study has shown that 【B19】 who had a view onto garden needed half the number of strong pain killers compared 【B20】 patients who had no view at all or only a brick wall to look at.

【B1】

A．air

B．environment

C．place

D．product

点击查看答案