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  3. A truly extraordinary variety of alternatives to the chemical control of insects is available. Some are already in use and have

A truly extraordinary variety of alternatives to the chemical control of insects is available. Some are already in use and have

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问题     A truly extraordinary variety of alternatives to the chemical control of insects is available. Some are already in use and have achieved brilliant success. Others are in the stage of laboratory testing. Still others are little more than ideas in the minds of scientists, waiting for the opportunity to put them to the test. All have this in common: they are biological solutions, based on understanding of the living organisms they seek to control, and of the whole structure of life to which these organisms belong. Specialists representing various areas of the vast field of biology are contributing, all pouring their knowledge and their creative inspirations into the formation of a new science of biological control. A century ago with the first attempts to introduce natural enemies of insects that were proving troublesome to farmers, the efforts sometimes moved slowly or not at all, but now and again gathered speed and momentum under the impetus of an outstanding success. Some of the most fascinating of the new methods are those that seek to turn the strength of a species against itself—to use the drive of an insect’s life forces to destroy it. The most spectacular of these approaches is the "male sterilization" technique developed by the chief of the U. S. Department of Agriculture’s Entomology Research Branch, Dr. Knipling and his associates.
    About a quarter of a century ago Dr. Knipling startled his colleagues by proposing a unique method of insect control. If it were possible to sterilize (使绝育) and release large numbers of insects, he theorized, the sterilized males would, under certain conditions, compete with the normal wild males so successfully that, after repeated releases, only infertile (不生育的) eggs would be produced and the population would die out.
"Alternatives to the chemical control" (Line 1) means_________.
选项 A、other kinds of chemical control of insects
B、altered methods of the chemical control of insects
C、ways other than the chemical to control insects
D、choices of chemicals to control insects
答案C
解析
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