单选题Medical experts have suspected for many years that there is a strong link between what a person eats and cancer. They say a new study provides the first evidence that vitamins could reduce a person' s chance of developing cancer. A team of Chinese and American scientists did the study. They are from American National Cancer Institute and the Cancer Institute of the Chinese Academy of Medical Sciences in Beijing. The Journal of the National Cancer Institute published the results of the study. There are more Chinese scientists than Americans in the team.A. RightB. WrongC. Not mentioned

单选题These products are {{U}}inferior to{{/U}} those we bought last year. A. poorer than B. narrower than C. larger than D. richer than

单选题They are concerned for the fate of the forest and the Indians who dwell in it.

单选题She is an artist whose work will undoubtedly withstand the test of time.

单选题{{B}}第三篇{{/B}} Why does cream go bad faster than butter? Some researchers think they found the answer, and it comes down to the structure of the food,not its chemical composition--a finding that could help rid some processed foods of chemical preservatives. Cream and butter contain pretty much the same substances, so why cream should sour much faster has been a mystery. Both are emulsions--tiny globules (小球) of one liquid evenly distributed throughout another. The difference lies in what's in the globules and what's in the surrounding liquid, says Brocklehurst, who led the investigation. In cream, fatty globules drift about in a sea of water. In butter, globules of a watery solution are locked away in a sea of fat. The bacteria which make the food go bad prefer to live in the watery colonies of the mixture. "This means that in cream, the bacteria are free to grow throughout the mixture," he says. When the situation is reversed, the bacteria are locked away in compartments (密封仓) buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients. They also slowly poison themselves with their waste products. "In butter, you get a self-limiting system which stops the bacteria growing," says Brocklehurst. The researchers are already working with food companies keen to see if their products can be made resistant to bacterial attack through alterations to the food's structure. Brocklehurst believes it will be possible to make the emulsions used in salad cream,for instance,more like that in butter. The key will be to do this while keeping the salad cream liquid and not turning it into a solid lump.

单选题It is not easy to tell anthrax from flu in the early days of the infection.

单选题 阅读下面的短文，文中有15处空白，每处空白给出4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 Many IQ tests show that there are no significant differences in the mean, or average scores of IQ tests between men and women. When a new IQ test, is being constructed, it is quite easy to find test{{U}} (51) {{/U}}that are not answered correctly{{U}} (52) {{/U}}the same proportions of men and women,{{U}} (53) {{/U}}these are usually then eliminated from the test. So, to some{{U}} (54) {{/U}}the fact that no differences are to be found in our current IQ tests between the{{U}} (55) {{/U}}for the two sexes is hardly surprising. There are,{{U}} (56) {{/U}}, differences in the standard deviations(偏差)or variability of the{{U}} (57) {{/U}}of the two sexes in many IQ tests,{{U}} (58) {{/U}}men showing the greater variation. The{{U}} (59) {{/U}}of many IQ test scores are such{{U}} (60) {{/U}}they approximate to the normal curve(正规曲线). If we regard some arbitrary lower score on a test as a classification like "educational subnormal(智力上逊常的人)" (ESN) and some equally arbitrary{{U}} (61) {{/U}}score as "gifted", we then find that there is higher ratio of ESN males to women and likewise we{{U}} (62) {{/U}}that there are more gifted men than women, even though the average scores are the same. The{{U}} (63) {{/U}}of men and women are known to differ somewhat in size, with women having about 200g less tissue{{U}} (64) {{/U}}the other hand, they also tend to{{U}} (65) {{/U}}less body mass, and over the phylogenetic(系统发育的)scale, the best index of species intelligence is the ratio of body mass to brain size.

单选题She persevered in her ideas despite obvious objections raised by friends.______

单选题{{B}}第二篇{{/B}} Between now(June) and Labor Day, millions of American will offer up their bodies to the sun's rays. A tan indicates health and beauty, and most sun worshippers will sacrifice a lot to achieve it—including themselves. With each hour, the sun's ultraviolet radiation produces irreversible damage, hastening the development of unsightly wrinkles. And with each year on the beach or rooftop, the sunbather increases his risk of getting skin cancer. Skin cancer is by far the most common form of cancer. An estimated 400000 new cases will be detected this year in the United States, and almost all of them can be blamed on overexposure to the sun. Fortunately, most of these cancers are highly curable. But they can be disfiguring and take time to treat. For that reason, sun worshippers should treat deity with a good deal of awe. Sunburn, of course, is the initial hazard posed by UV radiation. Prolonged exposure to UV, however, interferes with the production of collagen fibers in the dermis, causing the skin to lose elasticity and creating premature wrinkles. Further deterioration of the dermis deprives the epidermis of nutrition and causes it to become thin and dry. Cancer is UV's final insult. Short-wave radiant energy, especially from the UV-B band, breaks the strands of DNA. Enzymes work constantly to rearrange the DNA into proper sequence, but with repeated UV exposure, the repair process may eventually break down. Then the mutant DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense. People with fair skin and blue eyes who burn easily stand the highest risk. Special danger spots are the parts of the body most constantly exposed to the sun, such as the cheeks, nose, lower lip and the ears. People who have already developed precancerous lesions or had one skin cancer growth stand a greatly increased chance of developing others. Dermatologists recommend avoiding the sun when it is most intense—between 11 a.m. and 3 p.m. Anyone who insists on sunbathing should use a good sun screen. These lotions and salves contain chemicals, such as paraaminobenzoic acid, that block out the burning UV-B radiation while permitting the tanning rays to reach the skin.

单选题Preserving Nature for Future Demands for stronger protection for wildlife in Britain sometimes hide the fact that similar needs are felt in the rest of Europe. Studies by the Council of Europe, of which 21 countries are members, have shown that 45% of reptile(爬行动物) species and 24% of butterflies(蝴蝶)are in danger of dying out. European concern for wildlife was outlined by Dr. Peter Baum, an expert in the environment and natural resources division of the council, when he spoke at a conference arranged by the administrators of a British national park. The park is one of the few areas in Europe to hold the council"s diploma (证书 ) for nature reserves (自然保护区) of the highest quality, and Dr. Baum had come to present it to the park once again. He was afraid that public opinion was turning against national parks, and that those set up in the 1960s and 1970s could not be set up today. But Dr. Baum clearly remained a strong supporter of the view that natural environments needed. To be allowed to survive in peace in their own right. "No area could be expected to survive both as a true nature reserve and as a tourist attraction," he went on. The short sighted view that reserves had to serve immediate human demands for outdoor recreation(户外娱乐)should be replaced by full acceptance of their importance as places to preserve nature for the future. "We forget that they are the guarantee of life systems, on which any built-up area ultimately depends," Dr. Baum went on. "We could manage without most industrial products, but we could not manage without nature. However, our natural environment areas, which are the original parts of our countryside, have shrunk(缩小)to become mere islands in a spoiled and highly polluted Landmass. "

单选题 Motoring Technology 1.2 million road deaths worldwide occur each year, plus a further 50 million injuries. To reduce car crash rate, much research now is focused on safety and new fuels—though some electric vehicle and biofuel research aims at going faster. Travelling at speed has always been risky. One cutting edge area of research in motoring safety is the use of digital in-car assistants. They can ensure you don't miss crucial road signs or fall asleep. The use of artificial intelligence software allows these assistants to monitor your driving and makes sure your phone or radio doesn't distract you at a vital moment. Most crashes result from human and not mechanical faults. Some safety developments aim to improve your vision. Radar can spot obstacles in fog, while other technology "sees through" high-sided vehicles blocking your view. And improvements to seat belts, pedal controls and tyres are making driving smoother and safer. The colour of a car has been found to be linked with safety, as have, less surprisingly, size and shape. And alternatives to fossil-fuel based petrol, such as plant oils, are a hot area of research. Fuel cells based on hydrogen burn cleanly, and are the subject of a serious research effort. But whatever is in the fuel tank, you don't want a thief in the driving seat and there have been many innovations, some using satellite tracking and remote communications, to fight against car theft. These communication systems can also come into play if you crash, automatically calling for help. Accidents cause many traffic jams, but there are more subtle interplays between vehicles that can cause jams even on a clear but busy road. Such jams can be analysed using statistical tools. Robotic drivers could be programmed to make traffic flow smoothly and will perhaps one day be everyone's personal chauffeur, but their latest efforts suggest that won't be soon.

单选题An old friend called on me the day before yesterday.

单选题At 80, Peck was still vigorous and living in Paris.A. happyB. energeticC. aloneD. busy

单选题No rule of human conduct can be considered important in promoting the welfare of man unless

单选题These programmes are of immense value to old people.

单选题He was a much older tennis player but he had the great {{U}}advantage{{/U}} of experience.

单选题It is said that the houses along this street will soon be pulled down .

单选题Pushbike Peril Low speed bicycle crashes can badly injure — or even kill — children if they fall onto the ends of the handlebars. So a team of engineers is redesigning the humble handlebar in a bid to make it safer. Kristy Arbogast, a bioengineer at the Children's Hospital of Philadelphia in Pennsylvania, began the project with her colleagues after a study of serious abdominal injuries in children in the past 30 years showed that more than a third were caused by bicycle accidents. "The task was to identify how the injuries occurred and come up with some countermeasures," she says. By interviewing the children and their parents, Arbogast and her team were able tog reconstruct many of the accidents and identified a common mechanism responsible for serious injuries. They discovered that most occur when children hit an obstacle at a slow speed, causing them to topple over5. To maintain their balance they turn the handlebars through 90 degrees — but their momentum forces them into the end of the handlebars. The bike then falls over and the other end of the handlebars hits the ground, ramming it into their abdomen6. The solution the group came up with is a handgrip fitted with a spring and damping system. The spring absorbs up to 50 per cent of the forces transmitted through the handlebars in an impact. The group hopes to commercialize the device, which should add only a few dollars to the cost of a bike. "But our task has been one of education because up until now, bicycle manufacturers were unaware of the problem," says Arbogast. The team has also approached the US Consumer Product Safety Commission to try to persuade manufacturers to adopt the new design. A decision is expected later this year.

单选题In the 1950's accumulating scientific evidence linking cigarette smoking and lung cancer made a (51) impact (52) the smoking public. During this period many health agencies declared smoking to be a (53) Hazard. US Surgeon General Leroy E. Brunei said in 1957: "The weigh of the evidence is increasingly pointing to one direction: that (54) smoking is one of the causative factors in lung cancer." The initial reports had the heaviest impact, so (55) total cigarette production dropped in 1953 and again in 1954. (56) reports appeared to have less (57) on smoking habits, and by 1957 cigarette production had (58) above the 1952 level. (59) four voluntary health organizations urgued president John F. Kennedy to (60) a commission to study the widespread implications of the tobacco problem, the Surgeon General's Advisory Committee on Smoking and Health was (61) in 1962 to review and evaluate all (62) scientific data. When its report, Smoking and Health, was released in early 1964, cigarette consumption again declined (63) . Pipe and cigar smoking increased. More than 350, 000 copies of the report were contributed and sold. (64) abstracts and pamphlets were prepared by the Public Health Service and other organizations (65) a massive educational campaign on the hazards of cigarette smoking.

单选题We were Ushocked/U to find that Mary didn't know her guest's name.