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Genetically modified crops and foods having been launched by big companies bent on taking over agriculture, this new breakthroug

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问题     Genetically modified crops and foods having been launched by big companies bent on taking over agriculture, this new breakthrough in science poses a new problem—whether it’ s safe for people to eat them. Experts say that much of the current angst over genetically modified foods is unnecessary. If research and development are allowed to continue, the products will be there for all to appreciate.
    New varieties of rice and other crops, resistant to insects and diseases, will have replaced those cultivated today. Farmers will no longer lose substantial proportions of their harvests. The impact of these advances will be felt in the less developed countries. Health benefits will also come from plants genetically engineered to be more balanced nutritionally than those that have evolved through natural selection or been bred by traditional methods.
    The potential medical spin-offs from plant biotechnology are considerable. A new generation of more potent vaccines, many against illness for which no vaccines have been available, will be grown in plants such as maize and bananas.
    Malnutrition could be banished. Biotechnology can improve efficiency of food production and generate more nourishing crops.
    Throughout the world, gardeners, vegetarians, and consumers will benefit from plant varieties resistant to spoilage, foods which reduce our dependence on animals, and cheaper and/or tastier products.
    We should not, however, overlook potential hazards in altering our diets by genetic engineering. As with all other applications of science to human welfare, biotechnology is likely to have risks. Mistakes will probably be made.
    Nevertheless, any analysis of the new techniques for ferrying genes between plants must surely conclude that they are being applied and controlled more stringently than any technology ever before.
    Nearly 25 years ago, when scientists first learned to combine DNA from different sources, commentators warned of the iniquity of "opening Pandora’ s box". Among their horrific forecast were unstoppable epidemics and worldwide pestilence. None of these has come to pass, partly because genetic manipulation has not proved inherently dangerous.
    In addition, regulatory committees have been set up to ensure that experiments are conducted in appropriately safe conditions.
    The regulators’ task is not simply to allow research to go ahead unless potential hazards are obvious. It is to consider risks that could come to light later. Will a gene, introduced intorape to protect it against virus attack, also make the pollen grains more likely to cause hay fever? All proposals have to survive positive vetting of this sort before they are sanctioned.
    Genetic engineering is far more precise—and thus predictable—than the gene movements which occur in nature. When plants fertilize and cross-fertilize in the wild, large numbers of genes are transferred in a haphazard fashion.
    Biotechnology allows individual genes to be moved with precision from one plant to another. It is much easier to know how one gene will work in its new setting. The likelihood of unexpected consequences and the margin of error are correspondingly reduced.     There is a chance, however remote, that a gene introduced into a particular plant at one time and location might have adverse consequences if it eventually gets into another plant distant in space and time.
    Given the astronomical amount of random gene transfer which occurs through the biosphere such extreme caution is unwarranted. I believe most food producers—and eaters—would agree.
The expression "spin-offs" in Para. 3 refers to______.
选项 A、byproducts
B、bywork
C、side effects
D、consequences
答案A
解析 第三段提到The potential medical spin—offs from plant biotechnology are considerable．后面则举例说明：一种新的更有效的疫苗will be grown in plants such as maize and bananas．因此可推测出A项正确。byproduct副产品。by—work副业。side effect(药物等的)副作用。consequence结果。
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