题目内容
An epidemic of swine flu (猪流感) has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many people, and the outbreak has features that suggest it could become a global pandemic (瘟疫). A pandemic is an epidemic that spreads around the whole world. Pandemics also often cause more severe disease than epidemics. Flu is a disease caused by the influenza virus. Humans, pigs, birds and other animals all can be infected by influenza viruses. Typically, influenza viruses can infect only one species, so the influenza viruses of humans are different from those of pigs and birds. However, sometimes a virus can infect more than one species. For examples, pigs sometimes can be infected not only with pig influenza viruses, but also with human and bird influenza viruses. Then these viruses can come up to one another secretly and swap (交换) genes, creating new viruses that have a mix of genes -- from human, pig, and bird viruses. That is what has happened with this new swine flu virus. Sometimes this swapping of genes allows a virus that was originally able to infect only pigs or only birds to also infect humans. When that happens, we refer to the illness as "swine flu" or "bird flu". This current virus could actually be called "swine/bird flu", since it has some genes from pig flu viruses and other genes from bird flu viruses. Most viruses that cause swine flu or bird flu are very hard to pass from one human to another: they don’t cause epidemics. Sometimes, however, further changes in genes create a virus that can spread rapidly among humans, and can produce a more severe illness. One reason this illness is more severe is that the virus is so new. The regular flu that comes each year is caused by a regular human influenza virus that often has similarities to the viruses that have caused the flu in years past, so people have some degree of immunity to the latest virus. The unusual swine flu or bird flu viruses that develop the ability for person-to-person spread are so different that people have little or no immunity to them. The worst global pandemic in modem times was the influenza pandemic of 1918 to 1919. It affected about a third of the human race, and killed at least 40 million people in less than a year -- more than those who have been killed by AIDS in three decades. The world economy went into a deep recession. The average length of life dropped for 10 years. Unfortunately, the new swine flu virus can be transmitted between humans. It is not clear yet how easily it is transmitted, nor how it is transmitted. Almost surely it is transmitted by sneezing and coughing, and by skin-to-skin contact with an infected person. Which of the following is true about the present swine flu viruses
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The Future of Television: What’s on Next Bosses in the television industry have been keeping a nervous eye on two Scandinavians (斯堪的纳维亚人) with a reputation for causing trouble. In recent years Niklas Zennstrom, a Swede, and Janus Friis, a Dane, have frightened the music industry by inventing KaZaA, a "peer- to-peer" (P2P) file-sharing program that was widely used to download music without paying for it. Then they horrified the mighty telecoms industry by inventing Skype, another P2P program, which lets Internet users make free telephone calls between computers, and very cheap calls to ordinary phones. Their next move was to found yet another start-up -- this time, one that threatened to devastate (毁坏) the television industry. It may do the opposite, as it turns out. The new service, called Joost and now in advanced testing, is based on P2P software that runs on people’s computers, just like Skype and KaZaA. And it does indeed promise to transform the experience of watching television by combining what people like about old-fashioned TV with the exciting possibilities of the Internet. "But unlike KaZaA and Skype," says Fredrik de Wahl, a Swede whom Mr. Zennstrom and Friis have hired as Joost’s boss, "Joost does not disrupt the industry that it is entering. Instead, rather than undercutting television networks and producers, Joost might, as it were, give them new juice." That is because Mr. de Wahl and his Joost team, working mostly in the Netherlands, have bravely ignored the totems (图腾) of the Internet-video boom. Chief among these fashions is letting users upload anything they want to a video service -- which might include clips of themselves doing odd things ("user-generated content") or, more questionably, videos pirated from other sources. The celebrated example of this approach is YouTube, which is now part of Google, the leader in Internet search. Its big problem, however, is that it can be illegal (if copyright is violated) and terribly hard to turn into a business. On February 2nd Viacom, an American media giant, became the latest company to demand that YouTube remove copyright-infringing (侵犯版权的) clips from its website. YouTube has struck deals with some media firms, including NBC and CBS, to allow their material to appear on its site, and had been trying to thrash out a similar agreement with Viacom. Many observers regard Viacom’s move as a negotiating tactic. But whether YouTube can make money is unclear. Last month Chad Hurley, YouTube’s chief executive, sketched out plans for generating advertising revenues and sharing them with content providers, but so far his firm has none to speak of. The Innovation of Joost Joost is also ignoring the two business models seen as the most respectable alternatives to advertising. One is to make users pay for each television show or film they download, but then to let them keep it. This is the tack chosen by Apple, an electronics firm that sells videos on iTunes, its popular online store; by Amazon, the largest online retailer; and by Wal-Mart, the largest traditional retailer, which launched a video-download service this week. The other approach is to let users subscribe to what is, in effect, an all-you-can-eat buffet of videos, and then to "stream" video to their computers without leaving a permanent copy. This is the approach taken by, for instance, Netflix, a Californian firm that mostly delivers DVDs to its subscribers by post, but now also streams films. The reason that Joost is ignoring all of these methods, says Mr. de Wahl, is that none has much to do with the experience of simply watching TV, which most people enjoy. "Unlike the download or streaming approaches," he says, "TV is not about buying today what you want to watch tomorrow. It’s about turning it on and watching." And in contrast to the "lean-forward" context of "snacking" on a YouTube clip in one’s cubicle while the boss has stepped out, TV is a longer and more relaxed "lean-backward" experience. Hence Joost’s most shocking innovation, which is not to change the practices that TV adopted decades ago. It will be free, with advertising breaks -- no more than three minutes per hour -- either before, during or after a show, depending on the market. "Americans," says Mr. de Wahl, "are more tolerant of interruptions." Joost has "channels", like ordinary TV, but these are now playlists of videos that start whenever it is convenient to the viewer. Viewers can import their instant-messaging buddy lists and chat online with friends while watching the same program. For advertisers, such engagement is worth something, because the activity proves that somebody is watching, rather than being asleep or out of the room. Combined with other information, such as the computer’s IP address and hence its location, advertisers will be able to target their spots much more accurately -- all "Desperate Housewives" fans in a particular neighborhood, for example -- and thus ought to pay a premium. The Combination of Television and the Internet The thing that is missing in this new vision of television, however, is the set itself. Beaming video from a computer to a television is possible: Apple and other firms are starting to sell the necessary gadgets. But until it becomes much easier to connect televisions to the Internet, big media companies are likely to "wait and see" before committing to Joost, says Jeremy Allaire, the boss of Brightcove, a rival Internet-video firm based in Massachusetts. In the meantime, Mr. Allaire thinks, media firms are mainly interested in building their own brands, so Brightcove provides content owners with technology to show television on their own websites, syndicate their shows to other websites, track audiences and collect advertising revenue. There is, in short, no consensus about the best way to combine television with the Internet. Instead, there are a variety of experiments, of which Joost is the latest example and YouTube the best-known. But with telephony, the Internet is unpicking (拆开) service delivery from network ownership. Joost, YouTube, iTunes and Netflix do not need their own networks to supply their video services: they can rely on fast Internet links provided by others. According to iSuppli, a market-research firm, Internet downloads will claim more than one- third of the market for on-demand video by 2010. So just as Internet telephony has been bad for traditional phone companies, this "Internet bypass" could be bad for the "on demand" video services being offered by cable-TV and telecoms firms over their networks. But by bringing television to more screens, this could provide new models for program-makers to finance their productions and offer advertisers new ways to reach constraints. And so Joost and rival services could end up rejuvenating (使变得年轻) the 75-year-old medium. Joost’s innovative business model is free videos with ______.
Passage Three Questions 33 to 35 are based on the passage you have just heard.
The curse of jet lag has struck most international travelers at one time or another -- and anyone lucky enough to have avoided it will surely have suffered the equally unpleasant sleep-deprivation involved in an early-morning start. Nor, as shift workers know too, is it possible to escape by going to bed earlier the previous evening, and thus putting sleep in the bank. Sleepiness is controlled by the body’s internal biological clock, so an earlier bedtime just means several wakeful hours staring in frustration at a darkened ceiling. For years, some travelers and shift workers have sworn by melatonin (褪黑素). This is a hormone that regulates the biological clock. It is made in the brain by a structure called the pineal gland (松果体), as darkness sets in after sunset. Light is the one that keeps the biological clock in the same pace with solar time. The clock then tells the brain when to go to sleep. The theory of those who use melatonin is that an external dose of it can reset the clock, and thus cause the "go to sleep" signal to be sent at a more convenient moment~ Melatonin can also increase sleepiness during the day, when the pineal gland is not producing it. This has resulted in a growing, and often unregulated, market in melatonin-supplement tablets. The pharmaceutical industry’s response to this seems to be: "If you can’t beat them, join them." A paper in this week’s Lancet, by Shantha Rajaratnam of the Harvard Medical School and his colleagues, reports two trials, funded by drug companies, of tasimelteon, a substance that binds to the same receptors in the brain as melatonin does, and which it is expected will have a similar effect. In the course of these trials, more than 400 people had their bedtimes brought forward by five hours in controlled conditions. Half an hour before lights out, a quarter of them were given common drug, while the remaining three-quarters were given varying doses of tasimelteon. Dr. Rajaratnam and his colleagues report that the new drug let people fall asleep faster at the unnaturally early time, and also allowed them to sleep longer than those given the common one. Shantha Rajaratnam’s team finds that tasimelteon works ______ than melatonin.
硫脲类最严重的不良反应是
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