51. A company plans to develop a prototype weeding machine that uses cutting blades with optical sensors and microprocessorsthat distinguish weeds from crop plants by differences in shade of color . Theinventor of the machine claims that it will reduce labor costs by virtuallyeliminating the need for manual weeding. Which of the following is a consideration in favor of the company's implementing its plan to develop the prototype? (A) There is a considerable degree of variation in shade of colorbetween weeds of different species. (B) The shade of color of some plants tendsto change appreciably over the course of their growing season. (C) When crops are weeded manually, overallsize and leaf shape are taken into account in distinguishing crop plants from weeds. (D) Selection and genetic manipulationallow plants of virtually any species to be economically bred to have a distinctiveshade of color without altering their other characteristics. (E) Farm laborers who are responsible forthe manual weeding of crops carry out other agricultural duties at times in thegrowing season when extensive weeding is not necessary. 答案是D。。 求解释
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发表于 2011-7-11 17:01:58
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