单选题It is hard to track the blue whale, the ocean's largest creature, which has almost been killed off by commercial whaling and is now listed as an endangered species. Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior. So biologists were delighted early this year when with the help of the Navy they were able to track a particular blue whale for 33 days monitoring its sounds. This was possible because of the Navy's formerly top-secret system of underwater listening devices spanning the oceans. Tracking whales is but one example of an exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies. Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption (爆发) for the first time and that they plan similar studies. Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures. The speed of sound in water is roughly one mile a second—slower than through land but faster than through air. What is most important, different layers of ocean water can act as channels for sounds, focusing them in the same way a stethoscope (听诊器) does when it carries faint noises from a patient's chest to a doctor's ear. This focusing is the main reason that even relatively weak sounds in the ocean, especially low-frequency ones, can of- ten travel thousands of miles.

单选题Woman: Do you want the windows open or closed?Man: I almost always prefer fresh air, if possible.Question: What does the man imply?

单选题The national government is to make every effort to ______ the will of the people.

单选题A person may have an idea about himself that will prevent him from doing good work. He may have the idea that he is not capable of it. A child may think he is stupid because he does not understand how to make the most of his mental faculties, or he may accept another person's mistaken estimate of his ability. Older people may be handicapped by the mistaken belief that they are incapable of learning anything new because of their age. A person who believes that he is incapable will not make a real effort, because he feels that it would be useless. He won't go at a job with the confidence necessary for success. He is therefore likely to fail, and the failure will strengthen his belief in his incompetence. Alfred Adler, a famous doctor, had and experience which illustrates this. When he was a small boy he got off to a poor start in arithmetic. His teacher got the idea that he had no ability in arithmetic and told his parents what she thought in order that they would not expect too much of him. In this way, they too developed the idea, "Isn't it too bad that Alfred can't do arithmetic?" He accepted their mistaken estimate of his ability, felt that it was useless to try, and was very poor at arithmetic, just as they expected. One day Adler succeeded in solving a problem which none of the other students had been able to solve. This gave him confidence. He rejected the idea that he couldn't do arithmetic and was determined to show them that he could. His new found confidence stimulated him to go at arithmetic problems with a new spirit. He now worked with interest, determination, and purpose, and he soon became extraordinarily good at arithmetic. This experience made him realize that many people have more ability than they think they have, and that lack of success is often the result of lack of knowledge of how to apply one's ability, lack of confidence, and lack of determination as it the result of lack ability.

单选题There is no question that the old style of air pollution could kill people. In one week following the infamous "peasouper" fog in December 1952,4,700 people died in London. Most of these people were elderly and already had heart or lung diseases. A series of these killer fogs eventually led to the British Parliament passing the Clean Air Act which restricted the burning of coal. Fortunately the effect of smog on the lungs is not so dramatic. Scientists have now conducted a number of laboratory experiments in which volunteers are exposed to ozone inside a steel chamber for a few hours. Even at quite low concentrations there is a reversible fall in lung function, an increase in the irritability of the lungs and evidence of airway inflammation. Although irritable and inflamed lungs are particularly seen in people with asthma (哮喘) and other lung diseases, these effects of ozone also occur in healthy subjects. Similar changes are also seen after exposure to nitrogen dioxide, although there is some disagreement about the concentration at which they occur. Other studies have found that people living in areas with high levels of pollution have more symptoms and worse lung function than those living in areas with clean air. Groups of children attending school camps show falls in lung function even at quite low concentrations of ozone. There is also a relationship between ozone levels and hospital admissions for asthma, both in North America and Australia. It is suspected that long-term exposure to smog may result in chronic bronchitis (支气管炎) and emphysema (肺气肿), but this has yet to be proven. Recently an association has been found between the levels of particles in the air and death rates in North American cities. The reason for this association is not understood and as yet there is no evidence this occurs in Australia. However, we do know that hazy days are associated with more asthma attacks in children.

单选题By all means,call me whenever you have a problem.

单选题A: May I see your driving license and vehicle registration card? B: ______

单选题At last John Smith chose to (step down) as the company's chief executive and return to his roots in software research.

单选题Meanwhile, I always {{U}}kept in touch{{/U}} with my former professor at college, by letter and telephone.

单选题Terrorists rarely give any warnings, so what counts is ______ and quick response.

单选题African athletes ______ in their ability to win marathons and other events of long-distance running.

单选题The events of Sept. 11 have ratcheted up security at American airports to the highest level ever, according to a spokesman for Transportation Secretary Norman Mineta. But to say there is plenty of room for improvement puts it mildly: Hundreds of employees with access to high-security areas at 15 U. S. airports have been arrested or indicted by federal law enforcement officials for using phony social security numbers, lying about criminal convictions or being in the United States illegally. None of those arrested had terrorist links, but some aviation experts said the workers were in a position to help smuggle weapons or bombs aboard aircraft if they had wanted. Tests ordered by President Bush and conducted by federal agents at 32 airports between November and February, when airports were on highest alert, showed that Security screeners failed to detect knives 70% of the time, guns 300//00 of the time and simulated explosives 60% of the time. Two members of the House Transportation Committee are pushing to reverse the administration's opposition to arming pilots because groups representing pilots are insisting that their members need to be armed as a last line of defense. Attorney General John Ashcroft said the arrests of hundreds of airport employees showed that the system of background checks--done piecemeal by airlines, private contractors and others—needs tightening. That much is painfully obvious. What isn't clear is why the system was so porous (有洞的) to begin with and why it wasn't immediately tightened after that infamous Tuesday in September. Some people in the industry wisely have suggested that all airport workers be required to pass through the same metal detectors and other security checks as flight crews do. Congress has ordered the new Transpiration Security Administration to find ways to enact just such a requirement. Unfortunately, no deadline has been set, in part because federal officials are preoccupied with getting thousands of new baggage screeners in place by Nov. 19—when the reds take over airport security—and installing bomb-detection equipment in all airports by the end of the year. Plainly, those two goals are critical. But it would be a mistake to give low priority to fixing other gaping holes in the nation's airport security net. If the federal crackdown is going to be effective, it needs to be comprehensive.

单选题Sales of margarine rose last year ______those of butter.

单选题The microscope enables scientists to distinguish an (incredible) number and variety of bacteria.

单选题He claims that advertising today tends to Uportray/U women in traditional roles such as cooking or taking care of the baby.

单选题There are often discouraging predictions that have not been ______ by actual events.

单选题The government will take some action to______the two big quarreling companies.

单选题Three years have______since we last met at the conference for conternet communication in Beijing.

单选题"Employee commitment" in Paragraph 2 refers to the employee's______.