单选题It was not "the comet of the century" experts predicted it might be. However, Kohoutek has provided a bonanza of scientific information. It was first spotted 370 million miles from Earth, by an astronomer who was searching the sky for asteroids, and after whom the comet was named. Scientists who tracked Kohoutek the ten months before it passed the Earth predicted the comet would be a brilliant spectacle. But Kohoutek fell short of these predictions, disappointing millions of amateur sky watchers, when it proved too pale to be seen with the unaided eye. Researchers were very happy nonetheless with the new information they were able to glean from their investigation of the comet. Perhaps the most significant discovery was the identification of two important chemical compounds—methyl cyanide and hydrogen cyanide—never before seen in comets, but found it the far reaches of interstellar space. This discovery revealed new clues about the origin of comets. Most astronomers agree that comets are primordial remnants from the formation of the solar system, but whether they were born between Jupiter and Neptune or much farther out toward interstellar space has been the subject of much debate. If compounds no more complex than ammonia and methane, key components of Jupiter, were seen in comets, it would suggest that comets form within the planetary orbits. But more complex compounds, such as the methyl cyanide found in Kohoutek, point to formation far beyond the planets; there the deep freeze of space has kept them unchanged.

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单选题 The first big-name hackers include Steve Wozniak, Bill Gates and Linus Torvalds, all now highly recognisable names behind many of the computer technologies used today. These early hackers had a love of technology and a compelling need to know how it all worked, and their goal was to push programs beyond what they were designed to do. Back then, the word "hacker" didn't have the negative connotation it has today. The original hacker ethic, rooted out of simple curiosity and a need to be challenged, appears to be dead. The objectives of early hackers are a far cry from the goals of today's hacker. The motivation of the new breed of hackers appears not to be curiosity, or a hunger for knowledge, as it used to be. Instead, most of today's hackers are driven by greed, power, revenge, or some other malicious intent, treating hacking as a game or sport, employing the tools that are readily available via the Internet. The rate of security attacks is actually outpacing the growth of the Internet. This means that something besides the growth of the Internet is driving the rise in security attacks. Here are some realities you should know about: Operating systems and applications will never be secure. New vulnerabilities will be introduced into your environment every day. And even if you ever do get one operating system secure, there will be new operating systems with new vulnerabilities—phones, wireless devices, and network appliances. Employees will never keep up with security polices and awareness. It doesn't matter how much you train and educate your employees. If your employees disregard warnings about the hazards of opening questionable email attachments, how are you going to educate them about properly configuring firewalls and intrusion detection systems for their PCs? Managers have more responsibility than ever. And on top of the realities listed above, security managers are being asked to support increasing degrees of network availability and access. There are some good security measures you can take: Employ a layer 7, full-inspection firewall. Automatically update your anti-virus at the gateway, server and client. Keep all of your systems and applications updated. Hackers commonly break into a Web site through known security holes, so make sure your servers and applications are patched and up to date. Turn off unnecessary network services. Eliminate all unneeded programs. Scan network for common backdoor services—Use intrusion detection systems, vulnerability scans, anti-virus protection.

单选题— Who's that speaking? — ______. [A] I am Jack [B] This is Jack speaking [C] Jack is me

单选题 {{I}}Questions 11-13 are based on the following talk. You now have 15 seconds to read Questions 11-13.{{/I}}

单选题 Questions 17～20 are based on a conversation about hunting un apartment. You now have 20 seconds to read Questions 17～20.

单选题 Studies of the effect that makes many of us slumber or feel sleepy during the queen’s speech on Christmas Day have revealed that changes may be required in Britain’s drink drive legislation. Dr. James Home, director of the Sleep Research Laboratory at Loughborough University, is investigating pose-lunch sleepiness. We humans are designed to sleep twice a day, Once at night and a short nap after lunch, but in this part of the world we tend to repress that. It is a remnant of the same primeval programming that makes all animals in the bush rest in the hot afternoon sun to conserve energy. Hot environments make it worse and many cultures living near the equator, says Dr. Home, have conceded to be inevitable, where the afternoon siesta is the way of life. In this studies Dr. Home has been investigating the role of alcohol. The theory is that if you are more sleepy after lunch then it figures that alcohol will be more potent after lunch. One would figure then that a pint of beer at lunch time has more effect than in the evening, when people are more alert. Indeed, we find that it has about twice the effect. This has more sinister implications. If people take alcohol up to the legal driving limit, their performance is seriously impaired after lunch, said he. It seems that alcohol interacts with the circadian rhythm of sleep to cause afternoon sleepiness, so that one pint at lunch time is equivalent, in effect, to a quart in the evening. For this reason, most drivers ought not to drink at all at lunch time and the legal blood alcohol limit is no guide to "safe" driving here, said Dr. Home. For those who wish to enjoy the queen’s speech, Dr. Home recommends mild exercise, splash of cold air or cold water on the face, or a cup of coffee. Otherwise, take a cat nap. But this should be less than 15 minutes, otherwise, sleep really sets in and one can wake up feeling very groggy and far sleepier than to be in awake.

单选题What is the author's attitude in this article?

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单选题What is the attitude the author has toward eating meat?