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Across the United States, scientists are mounting what may become the most innovative agricultural research drive since the 1920

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问题      Across the United States, scientists are mounting what may become the most innovative agricultural research drive since the 1920s,when hybrid corn was developed. Surprisingly, the new genetic revolution is not taking place in America’s fields. Instead, it is occurring in biology laboratories, for it involves the deliberate manipulation in test tubes of the genes of crop plants. This genetic engineering may prove the biggest boon to agriculture since plant breeding began.
    The new concepts grew out of the bioengineering of bacteria for the production of such things as human hormones and vaccines for viral diseases. Plant cells, however, are far more complex than bacteria, and it will probably take many years for today’s encouraging laboratory results to have a major impact on the farm. In fact the payoff may not come until the next century.
    But although biotechnologists are still in the earliest phases of this new field of science, they are already actively exploring ways to redesign plants so they will use sunlight more efficiently, resist viruses and other pests, grow in hot or dry areas, in saline soils or in the presence of pesticides, and perhaps even make their own fertilizer out of nitrogen in the air.  In addition, scientists have had early success in making wholly new plants that are unavailable by conventional plant breeding--a potato-tomato combination, for example.
    The new technology holds the promise of virtually limitless horizons in food production. Only imagination sets the limits: frost-resistant wheat, tropical potatoes, saltwater rice, a plant producing a combination of a pea and a carrot--all may be with us one day.
From the passage we understand that conventional plant breeding produced ______.
选项 A、a potato-tomato hybrid
B、new plant technology
C、self-fertilizing plants
D、less dramatic results than the new technology
答案D
解析 本题为细节推断题。在第三段中提到“In addition，scientists have had early success in making wholly new plants that are unavailable by conventional plant breeding——a potato— tomato combination，for example．(另外，科学家们已经成功地研制出全新的植物，例如土豆和番茄的杂交品种，这是传统的植物培养技术望尘莫及的。)”由此可见，传统的植物培养技术无法培育出土豆和番茄的杂交品种，当然没有新技术那样不可思议。
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