单选题They all think that the prices of personal computers will soon plunge .

单选题He is renowned for his skill.

单选题The children’s story writer known as Dr. Seuss proved that the simplest stories for children could have characterization and suspense. A. structure B. history C. excitement D. plot

单选题Breastfeeding Can Cut Cardiovascular Risk Breastfeeding can reduce the risk of a heart attack or stroke later in life and could prevent hundreds of (51) of deaths each year, researchers said on Friday. Babies who are breastfed have fewer childhood infections and allergies and are less (52) to obesity. British scientists have now shown that breastfeeding and slow growth in the first weeks and months of life has a protective effect (53) cardiovascular disease. "Diets that promote more rapid growth put babies at risk many years later in (54) of raising their blood pressure, raising their cholesterol and increasing their tendency to diabetes and obesity--the (55) main risk factors for stroke and heart attack." said Professor Alan Lucas of the Institute of Child Health in London. "Our evidence suggests that the reason why breast-fed babies do better is because they grow more (56) in the early weeks." Lucas said the effects of breastfeeding on blood pressure and cholesterol later in life are greater than (57) adults can do to control the risk factors for cardiovascular disease, other than taking drugs. An estimated 17 million people die of (58) disease, particularly heart attack and strokes, each year, according to the World Health Organization. Lucas and his colleagues compared the health of 216 teenagers (59) as babies had either been breastfed or given different nutritional baby formulas'. They reported their (60) in The Lancet medical journal. The teenagers who had been (61) had a 14 percent lower ratio of bad to good cholesterol and lower concentrations of a protein that is a marker for cardiovascular disease risk. The researchers also found that (62) of the child's weight at birth, the faster the infants grew in the early weeks and months of life, the (63) was their later risk of heart disease and stroke. The effect was the (64) for both boys and girls. "The more human milk you have in the newborn period, the lower your cholesterol level is, the lower your blood pressure is 16 years (65) , "Lucas said.

单选题Before the first Apollo rocket went to the Moon, a spot for landing the lunar module was carefully chosen.

单选题But {{U}}in the end{{/U}} he approved of our proposal.

单选题Ford Abandons Electric Vehicles The Ford motor company's abandonment of electric cars effectively signals the end of the road for the technology, analysts say. General Motors and Honda ceased production of battery-powered cars in 1999, to focus on fuel cell and hybrid electric gasoline engines, which are more attractive to the consumer. Ford has now announced it will do the same. Three years ago, the company introduced the Think City two-seater car and a golf cart called the THINK, or Think Neighbor. It hoped to sell 5,000 cars each year and 10,000 carts. But a lack of demand means only about 1,000 of the cars have been produced, and less than 1,700 carts have been sold so far in 2002. "The bottom line is we don't believe that this is the future of environment transport for the mass market," Tim Holmes of Ford Europe said on Friday. "We feel we have given electric our best shot. " The Think City has a range of only about 53 miles and up to a six-hour battery recharge time. General Motors' EVI electric vehicle also had a limited range, of about 100 miles. The very expensive batteries also mean electric cars cost much more than petrol-powered alternatives. An electric Toyota RAV4 EV vehicle costs over $42,000 in the US, compared with just $17,000 for the petrol version. Toyota and Nissan are now the only major auto manufacturers to produce electric vehicles. "There is a feeling that battery electric has been given its chance. Ford now has to move on with its hybrid program, and that is what we will be judging them on, " Roger Higman, a senior transport campaigner at UK Friends of the Earth, told the Environment News Service. Hybrid cars introduced by Toyota and Honda in the past few years have sold well. Hybrid engines offer greater mileage than petrol-only engines, and the batteries recharge themselves. Ford says it thinks such vehicles will help it meet planned new guidelines on vehicle emissions in the US. However, it is not yet clear exactly what those guidelines will permit. In June, General Motors and Daimler Chrysler won a court injunction, delaying by two years Californian legislation requiring car-makers to offer 100,000 zero-emission and other low-emission vehicles in the state by 2003. Car manufacturers hope the legislation will be rewritten to allow for more low-emission, rather than zero-emission, vehicles.

单选题Half of world's primates face extinction Almost 50% of the world's 634 primate (灵长类动物) species face extinction, according to a report from the International Union for the Conservation of Nature. Habitat loss is a major cause, but many monkeys and apes are being hunted to extinction for food, especially in forests of south-east Asia. "It's cheaper to go into the forest and kill a monkey than to raise a chicken," says Jean-Christophe rie, deputy head of the IUCN's species programmeand a co—author of the report. "We've raised concerns for years about primates being in danger, but now we have solid data to show the situation is far more severe than we imagined," says Russell Mittermeier, president of Conservation International, which co-funded the study. The areas most at risk are in Vietnam and Cambodia, where 90% of species are being driven to extinction by demand for monkey meat and baby monkeys as pets. Most acutely affected are medium-sized monkeys such as gibbons(长臂猿), leaf monkeys and langurs, which are easy for hunters to track down and kill because of their size and the noise they make. In South America. spider monkeys and capuchin monkeys(卷尾猴)have been hit hardest. In Africa, red colobus monkeys are now critically endangered. Eleven of the 13 species assessed were listed as critically endangered or endangered. Two may already be extinct. " Among the African species, the great apes such as gorillas (大猩猩) and bonobos have always tended to grab the limelight, and even thought they're deeply threatened, it is smaller primates such as the red colobus that could die out first," says Richard Wrangham, president of the International Primatological Society. Huge political efforts are needed now to reverse the impending losses of threatened species, says Vid. "What's needed is national legislation to protect biodiversity, creation of protected areas with dedicated staff, crackdowns on corruption, and captive breeding programmes," he says. But it will be difficult to halt and reverse the damage done by habitat destruction and the hunters. Once habitat is gone, animals have nowhere to go. Also, killing primates rapidly depletes populations, because they have fewer young than many other mammals and take much longer to breed and raise families.

单选题The People's Republic of China was {{U}}established{{/U}} in 1949.

单选题He demolished my argument in minutes.

单选题The first step in planning a marketing strategy for a new product is to analyze the breakdown of sales figures for competitive products.

单选题It's all advisable idea to get out of the dispute. A. wise B. urgent C. useless D. proper

单选题His claims seem credible to many people.

单选题If headaches only occur at night, lack of fresh air is often the cause. A．start B．begin C．happen D．visit

单选题In a bullfight, it is movement, not the color, of subjects that arouses the bull.A. confusesB. excitesC. scaresD. diverts

单选题The Railway Labor Mediation Act of 1926 supported the use of collective bargaining to avert interruption of rail service.

单选题Human Evolution Being a man has always been dangerous. There are about 105 males born for every 100 females, but this ratio drops to near balance at the age of maturity, and among 70-year-old there are twice as many women as men. But the great universal of male mortality is being changed. Now, boy babies survive almost as well as girls do. This means that, for the first time, there will be an excess of boys in those crucial years when they are searching for a mate. More important, another chance for natural selection has been removed. Fifty years ago, the chance of a baby(particularly a boy baby) surviving depended on its weight. A kilogram too light or too heavy meant almost certain death. Today it makes almost no difference. Since much of the variation is due to genes, one more agent of evolution has gone. There is another way to commit evolutionary suicide : stay alive, but have fewer children. Few people are as fertile as in the past. Except in some religious communities, very few women have 15 children. Nowadays the number of births, like the age of death, has become average. Most of us have roughly the same number of offspring. Again, differences between people and the opportunity for natural selection to take advantage of it have diminished. India shows what is happening. The country offers wealth for a few in the great cities and poverty for the remaining tribal peoples. The grand mediocrity of today — everyone being the same in survival and number of offspring means that natural selection has lost 80% of its power in upper-middle-class India compared to the tribes. For us, this means that evolution is over; the biological Utopia has arrived. Strangely, it has involved little physical change. No other species fills so many places in nature. But in the past 100,000 years—even the past 100 years—our lives have been transformed but our bodies have not. We did not evolve, because machines and society did it for us. Darwin had a phrase to describe those ignorant of evolution: "they look at an organic being as average looks at a ship, as at something wholly beyond his comprehension. " No doubt we will remember a 20th century way of life beyond comprehension for its ugliness. But however amazed our descendants may be at how far from Utopia we were, they will look just like us.

单选题The story was touching .

单选题Flying the Hypert Skies A little airplane has given new meaning to the term "going hyper. " The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound. That's about 5,000 miles per hour. At this speed, you'd get around the world -- flying along the equator (赤道) -- in less than 5 hours. The Hyper-X is an unmanned,experimental aircraft just 12 feet long. It achieves hypersonic (超音速的) speed using a special sort of engine known as a scramjet. It may sound like something from a comic book,but engineers have been experimenting with scramjets since the 1960s. For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet (紧急刹车) engine goes as fast as a rocket, but it doesn't have to carry its own oxygen supply. A scramjet's special design allows it to obtain oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion (燃烧) flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound. A booster rocket carried the Hyper-X to an altitude of about 100,000 feet for its test flight. The aircraft's record-beating flight lasted just 11 seconds. Although the little plane's self-powered flight lasted only 11 seconds, that brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanes, comments Werner J. A. Dahm of the University of Michigan in Ann Arbor. In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Such hypersonic jets could potentially carry passengers anywhere in the world in just a few hours. Out of the three experimental Hyper-X aircrafts built for NASA, only one is now left. The agency has plans for another 11-second hypersonic flight, this time at 10 times the speed of the sound.

单选题Lake Erie is linked to Lake Ontario by the Niagara River. A. connected to B. turned into C. emptied into D. diverted to