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科学美国人60秒 SSS Computer security, curling, AAAS meeting

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Welcome to the Scientific American podcast for the seven days starting February 22nd. This week on the podcast, I'll talk to Scientific American senior writer Wayt Gibbs about computer security. Physicist1 Mark Shegelski gives us the cold hard facts about one of the cooler events at the Winter Olympics and frequent SciAm contributor JR Minkel reports on what he found at the largest general science conference of the year. Plus we'll test your knowledge of some recent science in the news.

First up, Scientific American senior writer Wayt Gibbs just got back from San Jose, California, in the heart of Silicon2 Valley, where he attended one the biggest computer security meetings of the year called the RSA Conference 2006. To get the lowdown on hi-tech security, I called Wayt at his home in Pittsburgh.

Steve: Hi, Wayt. How are you today?

Gibbs: Hi, I'm fine, thanks.

Steve: And you just got back from this conference. Tell us about it. What were some of the highlights?

Gibbs: This disturbing trend that many, many experts at this conference pointed3 out is that what used to be a kind of gentleman's game of the hackers4 looking for recognition or fame or infamy5 has turned into serious crime, and that's in fact of the malware or malformed software that's seen these days. Something like 99 percent of it is thought to be crimeware. Most of these are viruses and so-called Trojan horse program[s] that aim at co-opting a computer system and adding it to what they call a botnet. That is, they make it [a] sort of a robot system out of it that can be remote controlled by some malfeasant.

Steve: And what's the bottom line on this? How much money is being stolen this way?

Gibbs: Losses due to security breaches7 are now estimated at nearly 70 billion dollars a year—that's almost 200 million dollars a day. These estimates of course are very tricky8 to make because many, many computer crimes are not reported to the authorities. So this may be actually a very gross underestimate of the amount of computer crime going on. But the more alarming thing is the trend. The amount of dollar loss due to computer crimes seems to be growing at nearly three times the rate of investments in software and services to prevent computer crimes. So the bad guys are really outrunning the good guys.

Steve: What are the actual kinds of crimes that we're talking about?

Gibbs: A big one these days is extortion. I mentioned botnets earlier, where systems are taken over by hostile software and then they are used as launching pads for spam for so-called denial-of-service attacks, where they prevent some Web sites from operating. They take down the company's network.

Steve: So this is like an old-fashioned protection racket, where they don't actually do any damage unless you don't pay up.

Gibbs: Yes and from the Mafia's perspective, it's much superior to the old-fashioned racket, because it can be executed worldwide and because it doesn't require actual violence to enforce those who don't comply with your extortion request. Therefore the punishments, if you should be caught in it, are much less.

Steve: You don't have to break anybody's legs, you just press a few keystrokes and take down a whole industry.

Gibbs: In many countries, it's possible to operate these extortion rings with almost complete anonymityand almost complete protection from criminal prosecution9 by the law.

Steve: Amazing.

Gibbs: These botnets are huge. There was an arrest last month of three so-called bot herders who maintained one of these botnets, and they had more than 1.5 million machines under their control, unbeknownst, largely, to the owners of these machines.

Steve: All around the world…

Gibbs: They operated an extortion ring for months and they would just approach companies, tell them, "You will pay us x amount of dollars or we will destroy (laughs) your computer network"—and the alarming thing is that they operated for months overseas with no one reporting them to the authorities. When they struck a US firm, that company did report them to the FBI, and within hours, the FBI had taken them down.

Steve: All right! So that's the good news. In this case, at any rate, that if the authorities are notified, they apparently10 can do something about it relatively11 quickly.

Gibbs: Yes and no. In the case of extortion, they often can trace it to its source. Whether they can actually get an arrest and an extradition12 is another matter—it depends greatly on where the attack took place and what the laws are in that country. A lot of the criminals seen to be behind these attacks are part of the Russian mafia. And they operate in countries where it's very difficult to get the authorities to actually arrest the perpetrators and to recover any monies that have been taken. Another major source of crime on the Internet are [is] phishing attacks. These are fake Web sites that are set up to look like banking13 sites or pharmaceutical14 sites or other places where people might enter sensitive information. And they trick people via spam—or these days even by messages to cell phones—to go to these fake Web sites, enter their secure information and then, lo and behold15, all the money is transferred out of the account, or the secure information is used to commit crimes.

Steve: Incredible. It's absolute[ly] frightening and…

Gibbs: I'll tell you what frightens me. Phishing people are starting to become aware that they should never click on a link in an e-mail to go to a Web site where they would be entering password information. People are starting to learn to avoid this. But there is a much more insidious16 form of attack now taking place called pharming. Again, like phishing, this is spelled with a p-h at the beginning. The idea behind pharming is you actually poison the trust-based system of translation from network addresses such as wellsfargo.com to IP addresses such as 192.168.yadda yadda. By poisoning these servers and creating directories that are false, they can actually redirect legitimate17 traffic from the bank sites, say, to some site set up by, say the Russian mafia.

Steve: How are we going to defend against all this?

Gibbs: This is at root a social problem. As Kim Cameron, the chief architect for identity at Microsoft put it, "We need to think of humans as devices and these devices are fundamentally poor cryptographic devices that shift," so the humans are definitely the weak link in any security system, because they can be corrupted18, they can be tricked, they can make mistakes. We can't get humans out of the system because the system serves humans. So what's the solution? More education is part of it. Part of it is changing the level of trust that we use when we operate computer systems.

Steve: All right. Just be more careful in your personal use of computers.

Gibbs: Yeah. It seems clear that we need to raise people's level of suspicion, and the computer companies and the operating system companies, too, can do a lot to provide more clues that we can use and that we need to determine how suspicious we should be at anything that we see on our screen.

Steve: We're the weak link in the whole cyberworld apparently.

Gibbs: There's one other point that I want to mention. It's not just that computer security experts are seeing a dramatic increase in the number of online attacks, although that is impressive—one Boeing representative at the conference said that from 2002 she had seen an 11,000 percent increase in malware blocked at their corporate19 gateway—but more alarming is the increasing number of directed attacks. These are, instead of a virus or Trojan that's just sent on the Internet to go wherever it will go and to find its own way, these are attacks that are directed at a specific person, at a specific company—sometimes it is a specific machine. And Boeinghas reported attacks like of this kind that were attempts coming from China to steal specific engineering data on the Net.

Steve: So they identify an individual who may be working on something in a particular company and can target that individual's computer.

Gibbs: That's right. And these attacks are much harder to defend against because they do not spread widely. They generally do not get picked up by the detection network that feeds the antivirus, antispyware program, so their signatures are never entered into the database that is used to screen incoming software or incoming connections for possible malware, so they tend to fly their ware6 under the radar20 of the security software we have installed today.

Steve: That's scary stuff, Wayt, but thanks.

Gibbs: You're welcome.

Steve: For more on what Wayt found out at the RSA Conference 2006, check out the Scientific American blog at blog.sciam.com that's blog.s-c-i-a-m.com.

Now it’s time to play TOTALL.......Y BOGUS. Here are four science stories, three are true. See if you can deduce, induce into it reason, [or] just plain guess which one is TOTALL.......Y BOGUS.

Story number 1: Obesity21 may be contagious22. No, not because your brother passes the french fries, because he passes on a virus that increases fat deposits.

Story number 2: A study found that people who are better at tongue twisters, you know, like "a box of biscuits, a box of mix biscuits in a biscuit mixer," had much higher rates of gum disease than average.

Story number 3: While defending warrantless wiretaps, U.S. Attorney General Alberto Gonzales claimed that George Washington engaged in electronic surveillance.

And story number 4: The kind of earwax you have may be related to how you smell.

We'll be back with the answer. But first it's been called "chess on ice"—not hockey, that's foosball on ice—and most Americans only get a glimpse of this chess on ice every four years during the Olympics. We're talking about curling, the sport that looks like frozen shuffle23 board. One member of the team slides this 44-pound granite24 rock down the ice while two teammates with brooms feverishly25 sweep the ice in front of the sliding rock. The goal is to get your team's, big, heavy rocks closer to the bull's-eye than the other team's big, heavy rocks. Anyway, I was wondering where [what] all this sweeping26 was about and found a real scientist who studies curling. He is Mark Shegelski, a physicist at the University of Northern British Columbia, who usually researches odd quantum mechanical phenomena27 like quantum tunneling. But he used to do some curling and sometimes publishes on the physics of curling with fellow U.N.B.C. physicist Erik Jensen. I called Shegelski at his office in Prince George, British Columbia.

Steve: Professor Shegelski, thanks for being with us today.

Shegelski: Well, it's a pleasure. Thanks for contacting me.

Steve: The reason I got in touch was, I was watching curling during the Olympics and you see these people furiously sweeping the ice in front of this big, heavy granite rocks as it's going down the ice, and what are those sweepers actually accomplishing from a physics point of view?

Shegelski: Well, there is [are] several things. The most important one is that by sweeping in front of the ice, you are reducing the friction28 between the rock and the ice. With the reduced friction, the rock still slows down, but it doesn't slow down as quickly. You know, if you turn over a curling rock and look at it, you'll see that it is not the case of a circle in contact with the rock. It's a thin ring. The ice itself is also not flat, it's pebbled29. It has little hills and valleys, so that the actual area of contact is quite small, and therefore, there is a large pressure of the rock on the ice. In sweeping in front of the ice, you're bringing the temperature of the ice up and that reduces the friction. But you're also creating a thin dome30 of a quasi-liquid type of material. This is something that is not fully31 agreed upon by everybody, but you know, the work that we've done strongly supports the idea that the key thing going on is the friction that is due to this thin liquid film.

Steve: How many scholarly papers on curling have you published?

Shegelski: (laughs) More than I would like to admit. I don't actually remember how many I've published, but the one that's the most important in my opinion is the most recent paper that Doctor Erik Jensen and I elaborated on and published in the Canadian Journal of Physics in November 2004.

Steve: And that's "The Motion of Curling Rocks: Experimental Investigation32 and Semi-phenomenological Description."

Shegelski: Exactly!

Steve: So one of the big deals is that the rock, if I understand this correctly, the rock doesn't move in the direction that you would expect it to move. It's breaking in a way that you would expect not to happen based on the direction that the rock is spinning.

Shegelski: Correct.

Steve: So if it's spinning, let's say the rock is spinning clockwise, you'd expect it on dry ground, if you had something spinning clockwise on dry ground it would break to the left.

Shegelski: Yeah! You take a drinking glass and you turn the drinking glass over and rotate it clockwise and push it so it's sliding away from you. This glass will curl to the left as it goes away from you and that's exactly the opposite to what a curling rock does.

Steve: Okay, so what's going on? Do we know?

Shegelski: We investigated that rather thoroughly33, and one of the main things about this was that there'll be more melting of the thin liquid film at the front than at the back, and this thin film is very very thin to use. You can't observe it directly, but having more melting at the front of the rock than its back makes the friction at the front of the curling rock less than it is at the back, and so you can understand this by looking at the drinking glass and the curling rock. Let's take them both to be rotating clockwise and let's look first at the drinking glass, and as it lies on a countertop, the front of the drinking glass has a sideways motion to the right.

Steve: Okay.

Shegelski: And therefore the friction at the front will be to the left.

Steve: Right. I mean correct, to the left.

Shegelski: Yes.

Steve: Got it. The motion is to the right as it's turning clockwise, so the friction that it's encountering is going to the left.

Shegelski: Correct. The drinking glass has a tendency to shift forward. It doesn't actually lift off. The back doesn't actually lift off unless the friction is very high, but it has a tendency to push harder. It does push harder on the tabletop at the front than in the back, and therefore, the tabletop pushes harder back on the drinking glass up front as compared to the back. Now, being that the friction at the front is greater, as it has this stronger force from the friction at the back.

Steve: So that component34 is pushing it to the left as it moves forward.

Shegelski: That's right. At the front of the drinking glass, the sideways motion is to the right, the friction is to the left, and it's greater than what goes on at the back. At the back, the clockwise rotation35, the sideways motion [is] to the left and the friction is to the right, so the friction at the back is to the right, friction at the front is to the left, but the friction at the front is stronger than it is at the back.

Steve: Got it.

Shegelski: And that's what curling, the rotating drinking glass, curls to the left.

Steve: Right! But in your rock situation on the ice, because of what you just explained about the thin film up front, you have the opposite frictional situation.

Shegelski: Exactly. This is rolled to reverse. The friction at the front of the curling rock is less than it is at the back, and so therefore, the sideways component of the friction force at the back is to the right, and therefore, the curling rock curls to the right.

Steve: Very interesting. Doctor Shegelski, thank you very much.

Shegelski: Thank you.

Steve: If you are looking for more info or images that help to make this stuff clear, they are out there on the Web. Now the urls for those Web sites are pretty ugly, so just Google the professor's name, Shegelski, and you'll find them. That's Shegelski: s-h-e-g-e-l-s-k-i.

Now it’s time to find out which story was TOTALL.......Y BOGUS. Let us review the four stories, three of which are real.

Story number 1: A virus may contribute to obesity.

Story number 2: People good at tongue twisters get more gum disease.

Story number 3: The attorney general said that George Washington engaged in electronic surveillance.

And story number 4: Your earwax type and your body odor may be linked.

I'll give you a second to think about those. Time is up.

The link between viruses and obesity is true. In animal studies, a couple of adenoviruses have been implicated36 in increasing fat levels. You should still eat right, get exercise and wash your hands to try to keep from being infected.

The story about the attorney general and George Washington, well, here's what he said.

Gonzalez: President Washington, President Lincoln, President Wilson, President Roosevelt, have all authorized37 electronic surveillance.

Steve: Now he didn't explain how George Washington did electronic surveillance, but I have a good authority that it involved trained eels38, trained eels.

The one about earwax and body odor is true. There are basically two kinds of earwax—known as wet and dry—and researchers studying earwax genetics say that people with the wet kind generally have more unpleasant armpit odor than people with the dry kind. There is a correlation39 there.

Which means that the story about tongue twisters and gum disease is TOTALL.......Y BOGUS. Nevertheless, Theophilus Thistle was a successful thistle sifter40.

Next up, frequent Scientific American Magazine contributor JR Minkel. He just returned from the biggest general science conference of the year, the annual meeting of the American Association for the Advancement41 of Science, usually just called the AAAS. To find out what JR found out, I called him at his home in Brooklyn, New York.

Steve: Hi, JR. How are you?

Minkel: I'm pretty good. Hi, Steve.

Steve: So you just got back from the AAAS Conference in Saint Louis. What in your opinion were some of the more interesting stories that you ran into there?

Minkel: Yeah. There were a few stories that I like. One of the topics being addressed was the changing nature of mathematical proof. Keith Devlin from Stanford University, who has written lot of popular books on mathematics, spoke42 about that. Though the idea there is that in the past, say, 50 years, there have been a few major examples of mathematical proofs that are so, you know, horribly long and complicated, possibly needing a computer to run, that mathematicians44 can't actually say with certainty that the proof is proved. The four-color theorem was originally checked by—it involved the checking through a number of different cases by computer, and at the same time, it came out, it was somewhat controversial whether that actually constituted a proof because you had to, you know, accept that the computer was doing this. But no single mathematician43 or may be even a group of them could check all the lines of the code, all these cases the computer was checking.

Steve: And the four-color theorem is the one about that you only need four colors to do any kind of math.

Minkel: Right!

Steve: No two countries with the same color would be next to each other, with only four colors being enough.

Minkel: Right! And so there were [a] couple of other examples. The Kepler conjecture45, which has to do with what's the most the least wasteful46 way to pack spheres. The intuition of that is the way that a grocer would do it, by, you know, the way [a] grocer would arrange oranges or grapefruit is the best way to do it, the way that makes the most use of the space. But actually proving that was terribly complicated and required this long, computerated proof that came out a few years ago. And it was submitted to, I think, the Annals of Mathematics, and they reviewed it, came back and said, "Well, we, you know, we're 99 percent sure that this is true, but we can't check every line of the computer code, so that’s the best we can do," and the paper was, I believe, published with a little note saying something to that effect.

Steve: And the packing problem is really advantageous47 to manufacturing, for example, because they would love to know if there is a way to get more spherical48 objects in the same size box.

Minkel: Yeah! You know, you could fit more golf balls into a box. That, you know, I would love to know.

Steve: How do we know that something is absolutely proven in a mathematical sense? What do we really know about the nature of mathematical proof?

Minkel: So what it means is it's believed that we have to take [a] mathematician's word for it. We have to take the word of the people who know the problem best. So that one point is that basically, there might be a few sort of high-profile example[s] of cases in which we cannot say with ironclad certainty that this is true, but that just makes mathematics sort of like, more like, other sciences.

Steve: So the old proverb about "trust but verify" in mathematics has become just trust?

Minkel: Well, in some cases, yes.

Steve: What else do you have from the meeting?

Minkel: There is a, you know, a cute symposium49 on how insects fly. I think the highlight from that was a neuroscientist at Caltech, who, so he pointed out at this point, we you know mathematicians have given a, say, a rough but good understanding of the basic forces that a wing creates when it is flapping, and the question now is how to use that knowledge to figure out how a fly, for example, you know, flies around, find[s] things, navigates50 in the environment based on the fundamental way that it's going to work; how does it control the wings. Though he is trying to reverse engineer the fruit fly, as he says, and that he started out with putting sensors51 on insect wings, and has now moved to what he calls the GUFM, the grand unified52 fly model, which is a simulation of a flapping, navigating53 fly.

Steve: What is the researcher's name?

Minkel: His name is Michael Dickinson.

Steve: And what does he hope to accomplish by getting a better understanding of insect flight?

Minkel: I mean there is a one sort of obvious application, which is, you know, the government would like to have really small robots that can fly around then, and then spy on, you know, whoever. So there is an application to little flying vehicles, but it's also just sort of an interesting problem.

Steve: Anything else that turned up interesting at the conference?

Minkel: Yeah. There was another cool one. Human evolution is always sort of popular at these meetings, and there was another cute talk about the possibility that eating more fish and shellfish fuels the growth of our brain. And that fish provide a high-quality, long chain, polyunsaturated fatty acids, which are very useful in the developing brain.

Steve: These are the omega-3s that you always hear about?

Minkel: Yeah, and the idea is that after some climatic changes, the environment became wetter and we had more access driven to getting more fish and that'll be, you know, having more of those omega-3s presumably, you know, or either drove the growth of our brain, or gave us the fuel with which we have bigger brains.

Steve: So fish really is brain food.

Minkel: Apparently.

Steve: Interesting stuff. Thanks very much, JR.

Minkel: Sure. Thanks, Steve.

Steve: For more info on the AAAS meeting, go to www.aaas.org.

Well! that's it for this edition of the Scientific American podcast. Our e-mail address is [email protected]. Remember, SciAm in this case has nothing to do with Thailand. SciAm is short for Scientific American, so the e-mail address is [email protected]. And also remember that science news is updated daily on the Scientific American Web site, www.sciam.com – www.s-c-i-a-m.com. I am Steve Mirsky. Thanks for clicking on us.


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点击收听单词发音收听单词发音  

1 physicist oNqx4     
n.物理学家,研究物理学的人
参考例句:
  • He is a physicist of the first rank.他是一流的物理学家。
  • The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
2 silicon dykwJ     
n.硅(旧名矽)
参考例句:
  • This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
  • A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。
3 pointed Il8zB4     
adj.尖的,直截了当的
参考例句:
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
4 hackers dc5d6e5c0ffd6d1cd249286ced098382     
n.计算机迷( hacker的名词复数 );私自存取或篡改电脑资料者,电脑“黑客”
参考例句:
  • They think of viruses that infect an organization from the outside.They envision hackers breaking into their information vaults. 他们考虑来自外部的感染公司的病毒,他们设想黑客侵入到信息宝库中。 来自《简明英汉词典》
  • Arranging a meeting with the hackers took weeks againoff-again email exchanges. 通过几星期电子邮件往来安排见面,他们最终同意了。 来自互联网
5 infamy j71x2     
n.声名狼藉,出丑,恶行
参考例句:
  • They may grant you power,honour,and riches but afflict you with servitude,infamy,and poverty.他们可以给你权力、荣誉和财富,但却用奴役、耻辱和贫穷来折磨你。
  • Traitors are held in infamy.叛徒为人所不齿。
6 ware sh9wZ     
n.(常用复数)商品,货物
参考例句:
  • The shop sells a great variety of porcelain ware.这家店铺出售品种繁多的瓷器。
  • Good ware will never want a chapman.好货不须叫卖。
7 breaches f7e9a03d0b1fa3eeb94ac8e8ffbb509a     
破坏( breach的名词复数 ); 破裂; 缺口; 违背
参考例句:
  • He imposed heavy penalties for breaches of oath or pledges. 他对违反誓言和保证的行为给予严厉的惩罚。
  • This renders all breaches of morality before marriage very uncommon. 这样一来,婚前败坏道德的事就少见了。
8 tricky 9fCzyd     
adj.狡猾的,奸诈的;(工作等)棘手的,微妙的
参考例句:
  • I'm in a rather tricky position.Can you help me out?我的处境很棘手,你能帮我吗?
  • He avoided this tricky question and talked in generalities.他回避了这个非常微妙的问题,只做了个笼统的表述。
9 prosecution uBWyL     
n.起诉,告发,检举,执行,经营
参考例句:
  • The Smiths brought a prosecution against the organizers.史密斯家对组织者们提出起诉。
  • He attempts to rebut the assertion made by the prosecution witness.他试图反驳原告方证人所作的断言。
10 apparently tMmyQ     
adv.显然地;表面上,似乎
参考例句:
  • An apparently blind alley leads suddenly into an open space.山穷水尽,豁然开朗。
  • He was apparently much surprised at the news.他对那个消息显然感到十分惊异。
11 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
12 extradition R7Eyc     
n.引渡(逃犯)
参考例句:
  • The smuggler is in prison tonight,awaiting extradition to Britain.这名走私犯今晚在监狱,等待引渡到英国。
  • He began to trouble concerning the extradition laws.他开始费尽心思地去想关于引渡法的问题。
13 banking aySz20     
n.银行业,银行学,金融业
参考例句:
  • John is launching his son on a career in banking.约翰打算让儿子在银行界谋一个新职位。
  • He possesses an extensive knowledge of banking.他具有广博的银行业务知识。
14 pharmaceutical f30zR     
adj.药学的,药物的;药用的,药剂师的
参考例句:
  • She has donated money to establish a pharmaceutical laboratory.她捐款成立了一个药剂实验室。
  • We are engaged in a legal tussle with a large pharmaceutical company.我们正同一家大制药公司闹法律纠纷。
15 behold jQKy9     
v.看,注视,看到
参考例句:
  • The industry of these little ants is wonderful to behold.这些小蚂蚁辛勤劳动的样子看上去真令人惊叹。
  • The sunrise at the seaside was quite a sight to behold.海滨日出真是个奇景。
16 insidious fx6yh     
adj.阴险的,隐匿的,暗中为害的,(疾病)不知不觉之间加剧
参考例句:
  • That insidious man bad-mouthed me to almost everyone else.那个阴险的家伙几乎见人便说我的坏话。
  • Organized crime has an insidious influence on all who come into contact with it.所有和集团犯罪有关的人都会不知不觉地受坏影响。
17 legitimate L9ZzJ     
adj.合法的,合理的,合乎逻辑的;v.使合法
参考例句:
  • Sickness is a legitimate reason for asking for leave.生病是请假的一个正当的理由。
  • That's a perfectly legitimate fear.怀有这种恐惧完全在情理之中。
18 corrupted 88ed91fad91b8b69b62ce17ae542ff45     
(使)败坏( corrupt的过去式和过去分词 ); (使)腐化; 引起(计算机文件等的)错误; 破坏
参考例句:
  • The body corrupted quite quickly. 尸体很快腐烂了。
  • The text was corrupted by careless copyists. 原文因抄写员粗心而有讹误。
19 corporate 7olzl     
adj.共同的,全体的;公司的,企业的
参考例句:
  • This is our corporate responsibility.这是我们共同的责任。
  • His corporate's life will be as short as a rabbit's tail.他的公司的寿命是兔子尾巴长不了。
20 radar kTUxx     
n.雷达,无线电探测器
参考例句:
  • They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
  • Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。
21 obesity Dv1ya     
n.肥胖,肥大
参考例句:
  • One effect of overeating may be obesity.吃得过多能导致肥胖。
  • Sugar and fat can more easily lead to obesity than some other foods.糖和脂肪比其他食物更容易导致肥胖。
22 contagious TZ0yl     
adj.传染性的,有感染力的
参考例句:
  • It's a highly contagious infection.这种病极易传染。
  • He's got a contagious laugh.他的笑富有感染力。
23 shuffle xECzc     
n.拖著脚走,洗纸牌;v.拖曳,慢吞吞地走
参考例句:
  • I wish you'd remember to shuffle before you deal.我希望在你发牌前记得洗牌。
  • Don't shuffle your feet along.别拖着脚步走。
24 granite Kyqyu     
adj.花岗岩,花岗石
参考例句:
  • They squared a block of granite.他们把一块花岗岩加工成四方形。
  • The granite overlies the older rocks.花岗岩躺在磨损的岩石上面。
25 feverishly 5ac95dc6539beaf41c678cd0fa6f89c7     
adv. 兴奋地
参考例句:
  • Feverishly he collected his data. 他拼命收集资料。
  • The company is having to cast around feverishly for ways to cut its costs. 公司迫切须要想出各种降低成本的办法。
26 sweeping ihCzZ4     
adj.范围广大的,一扫无遗的
参考例句:
  • The citizens voted for sweeping reforms.公民投票支持全面的改革。
  • Can you hear the wind sweeping through the branches?你能听到风掠过树枝的声音吗?
27 phenomena 8N9xp     
n.现象
参考例句:
  • Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
  • The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系,如果存在着任何联系的话。
28 friction JQMzr     
n.摩擦,摩擦力
参考例句:
  • When Joan returned to work,the friction between them increased.琼回来工作后,他们之间的摩擦加剧了。
  • Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体,并使其停止。
29 pebbled 9bbe16254728d514f0c0f09c8a5dacf5     
用卵石铺(pebble的过去式与过去分词形式)
参考例句:
  • And quick to the white-pebbled bottom it fell! 接着它飞快地回落到白色卵石的井底潺潺!
  • Outside, the rain had stopped but the glass was still pebbled with bright drops. 窗外的雨已经停了,但玻璃上还是布满明亮的水珠。
30 dome 7s2xC     
n.圆屋顶,拱顶
参考例句:
  • The dome was supported by white marble columns.圆顶由白色大理石柱支撑着。
  • They formed the dome with the tree's branches.他们用树枝搭成圆屋顶。
31 fully Gfuzd     
adv.完全地,全部地,彻底地;充分地
参考例句:
  • The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气,然后全部呼出。
  • They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
32 investigation MRKzq     
n.调查,调查研究
参考例句:
  • In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
  • He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。
33 thoroughly sgmz0J     
adv.完全地,彻底地,十足地
参考例句:
  • The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
  • The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。
34 component epSzv     
n.组成部分,成分,元件;adj.组成的,合成的
参考例句:
  • Each component is carefully checked before assembly.每个零件在装配前都经过仔细检查。
  • Blade and handle are the component parts of a knife.刀身和刀柄是一把刀的组成部分。
35 rotation LXmxE     
n.旋转;循环,轮流
参考例句:
  • Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
  • The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。
36 implicated 8443a53107b44913ed0a3f12cadfa423     
adj.密切关联的;牵涉其中的
参考例句:
  • These groups are very strongly implicated in the violence. 这些组织与这起暴力事件有着极大的关联。 来自《简明英汉词典》
  • Having the stolen goods in his possession implicated him in the robbery. 因藏有赃物使他涉有偷盗的嫌疑。 来自《现代汉英综合大词典》
37 authorized jyLzgx     
a.委任的,许可的
参考例句:
  • An administrative order is valid if authorized by a statute.如果一个行政命令得到一个法规的认可那么这个命令就是有效的。
38 eels eels     
abbr. 电子发射器定位系统(=electronic emitter location system)
参考例句:
  • Eels have been on the feed in the Lower Thames. 鳗鱼在泰晤士河下游寻食。
  • She bought some eels for dinner. 她买回一些鳗鱼做晚餐。
39 correlation Rogzg     
n.相互关系,相关,关连
参考例句:
  • The second group of measurements had a high correlation with the first.第二组测量数据与第一组高度相关。
  • A high correlation exists in America between education and economic position.教育和经济地位在美国有极密切的关系。
40 sifter SiCz6X     
n.(用于筛撒粉状食物的)筛具,撒粉器;滤器;罗圈;罗
参考例句:
  • She sifted thistles through her thistle-sifter. 她用蓟筛筛蓟。 来自《简明英汉词典》
  • This paper deals with a nitempering process of sifter mesh. 研究了一种筛片的软氮化工艺。 来自互联网
41 advancement tzgziL     
n.前进,促进,提升
参考例句:
  • His new contribution to the advancement of physiology was well appreciated.他对生理学发展的新贡献获得高度赞赏。
  • The aim of a university should be the advancement of learning.大学的目标应是促进学术。
42 spoke XryyC     
n.(车轮的)辐条;轮辐;破坏某人的计划;阻挠某人的行动 v.讲,谈(speak的过去式);说;演说;从某种观点来说
参考例句:
  • They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
  • The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。
43 mathematician aoPz2p     
n.数学家
参考例句:
  • The man with his back to the camera is a mathematician.背对着照相机的人是位数学家。
  • The mathematician analyzed his figures again.这位数学家再次分析研究了他的这些数字。
44 mathematicians bca28c194cb123ba0303d3afafc32cb4     
数学家( mathematician的名词复数 )
参考例句:
  • Do you suppose our mathematicians are unequal to that? 你以为我们的数学家做不到这一点吗? 来自英汉文学
  • Mathematicians can solve problems with two variables. 数学家们可以用两个变数来解决问题。 来自哲学部分
45 conjecture 3p8z4     
n./v.推测,猜测
参考例句:
  • She felt it no use to conjecture his motives.她觉得猜想他的动机是没有用的。
  • This conjecture is not supported by any real evidence.这种推测未被任何确切的证据所证实。
46 wasteful ogdwu     
adj.(造成)浪费的,挥霍的
参考例句:
  • It is a shame to be so wasteful.这样浪费太可惜了。
  • Duties have been reassigned to avoid wasteful duplication of work.为避免重复劳动浪费资源,任务已经重新分派。
47 advantageous BK5yp     
adj.有利的;有帮助的
参考例句:
  • Injections of vitamin C are obviously advantageous.注射维生素C显然是有利的。
  • You're in a very advantageous position.你处于非常有利的地位。
48 spherical 7FqzQ     
adj.球形的;球面的
参考例句:
  • The Earth is a nearly spherical planet.地球是一个近似球体的行星。
  • Many engineers shy away from spherical projection methods.许多工程师对球面投影法有畏难情绪。
49 symposium 8r6wZ     
n.讨论会,专题报告会;专题论文集
参考例句:
  • What have you learned from the symposium?你参加了这次科学讨论会有什么体会?
  • The specialists and scholars present at the symposium come from all corners of the country.出席研讨会的专家学者们来自全国各地。
50 navigates 958df1f5bfaf5943d4890ea6c3cd4bd4     
v.给(船舶、飞机等)引航,导航( navigate的第三人称单数 );(从海上、空中等)横越;横渡;飞跃
参考例句:
  • Dolpins also navigates by some kind of echo system. 原来海豚也是借助某种回声系统寻向的。 来自辞典例句
  • Navigates in menus, lists, choice screens and into edited texts. 可以操纵菜单、列表、屏幕选项和进入编辑文本。 来自互联网
51 sensors 029aee483db9ae244d7a5cb353e74602     
n.传感器,灵敏元件( sensor的名词复数 )
参考例句:
  • There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
  • Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时,有很大变化。 来自辞典例句
52 unified 40b03ccf3c2da88cc503272d1de3441c     
(unify 的过去式和过去分词); 统一的; 统一标准的; 一元化的
参考例句:
  • The teacher unified the answer of her pupil with hers. 老师核对了学生的答案。
  • The First Emperor of Qin unified China in 221 B.C. 秦始皇于公元前221年统一中国。
53 navigating 7b03ffaa93948a9ae00f8802b1000da5     
v.给(船舶、飞机等)引航,导航( navigate的现在分词 );(从海上、空中等)横越;横渡;飞跃
参考例句:
  • These can also be very useful when navigating time-based documents, such as video and audio. 它对于和时间有关的文档非常有用,比如视频和音频文档。 来自About Face 3交互设计精髓
  • Vehicles slowed to a crawl on city roads, navigating slushy snow. 汽车在市区路上行驶缓慢,穿越泥泞的雪地。 来自互联网

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