Supermarket shoppers have never been more spoilt for choice. But just when we thought traditional systems of selective farming h

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问题 Supermarket shoppers have never been more spoilt for choice. But just when we thought traditional systems of selective farming had created the most tempting array of foods money can buy, we are now being presented with the prospect of genetically created strains of cabbages, onion, tomato, potato and apple.
It may not tickle the fancy of food purists but it fires the imagination of scientists. Last week they discovered that the classic Parisian mushroom contains just the properties that, when genetically mixed with a wild strain of mushroom from the Sonora desert in California, could help it grow en masse while at the same time providing it with the resilience of the wild strain.
【R1】______
" We have found a way of increasing the success rate from one to 90 per cent.
This is just one of the many products that, according to skeptics, are creating a generation of "Frankenfoods". The first such food that may be consumed on a wide scale is a tomato which has been genetically manipulated so that it does not soften as it ripens.
【R2】______
Critics say that the new tomato—which cost $ 25 million to research—is designed to stay on supermarket shelves for longer. It has a ten-day life span.
Not surprisingly, every-hungry US is leading the search for these forbidden fruit. By changing the genes of a grapefruit, a grower from Texas has created a sweet, red, thin-skinned grapefruit expected to sell at a premium over its California and Florida competitors.
For chip fanatics who want to watch their waist-lines, new high-starch, low-moisture potatoes that absorb less fat when fried have been created, thanks to a gene from intestinal bacteria.
The scientists behind such new food argue that genetic engineering is simply an extension of animal and plant breeding methods and that by broadening the scope of the genetic changes that can be made, sources of food are increased. Accordingly , they argue, this does not inherently lead to foods that are less safe than those developed by conventional techniques. But if desirable genes are swapped irrespective of species barriers, could things spiral out of control? "Knowledge is not toxic, "said Mark Cantley, head of the biotechnology unit at the Organisation for Economic Co-operation and Development , " It has given us a far greater understanding of how living systems work at a molecular level and there is no reason for people to think that scientists and farmers should use that knowledge to do risky things.
Clearly, financial incentive lies behind the development of these bigger, more productive foods. But we may have only ourselves to blame. In the early period of mass food commerce, food varieties were developed by traditional methods of selective breeding to suit the local palate. But as suppliers started to select and preserve plant variants that had larger fruit, consumer expectations rose, leading to the development of the desirable clones. Still, traditionalists and gourmets in Europe are fighting their development.
【R3】______
Even in the pre-packaged US, where the slow-softening tomato will soon be reaching supermarkets, 1, 500 American chefs have lent their support to the Pure Food Campaign which calls for the international boycott of genetically engineered foods until more is known about the consequences of the technology and reliable controls have been introduced.
In the short term, much of the technology remains untested and in the long term the consequences for human biology are unknown. Questions have arisen over whether new proteins in genetically modified food could cause allergies in some people.
【R4】______
Then there are the vegetarians who may be consuming animal non-vegetable proteins in what they think is a common tomato, or the practicing Jew who unknowingly consumes a fruit that has been enhanced with a pig’s gene. As yet, producers are under no obligation to label "transgeneic" products.
Environmentalists worry that new, genetically engineered plants may damage natural environment. A genetically engineered pest-resistant strain of plant that contacts with a native strain, for example, could turn them into virulent weeds beyond chemical control.
Animal welfare groups worry about the quality of life of farm animals manipulated so that they produce more meat, milk, and eggs but which may suffer physical damage in the process.
【R5】______
Many of these fears spring from ignorance. And although it is hard to separate the paranoia from the benefits, the fact remains that genetic engineering offers ways of solving serious medical and agricultural problems.
A. Western farmers have already bred cattle with more muscle than a skeleton can carry.
B. Supporters say the tomato, unsurprisingly called Flavr Savr, will taste better because it will be able to mature on the branch longer.
C. Consumer opposition means that there are genetically manipulated foods on the German markets, and the Norwegian government has recently put research into genetically engineered foods on hold.
D. For example, if a corn gene is introduced into a wheat gene for pest resistance, will those who are allergic to corn then be allergic to wheat?
E. " Mushrooms in the past were almost impossible to cross, " says Philippe Callac, one of the three scientists working on the mushroom.
F. Genetic engineering will interfere with the balance of nature.
【R4】

选项

答案D

解析由上一段最后一句可知，只有D放在此处才能连贯，D为上一段最后一句的举例。

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Supermarket shoppers have never been more spoilt for choice. But just when we thought traditional systems of selective farming h

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