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Passage Four Even plants can run a fever, especially when they’re under attack by insects or disease. But unlike humans, plants can have their temperature taken from 3,000 feet away——straight up. A decade ago, adapting the infrared (红外线) scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers pre-cisely target pesticide (杀虫剂) spraying rather than rain poison on a whole field, which in- variably includes plants that don’t have pest (害虫) problems. Even better, Paley’s Remote Scanning Services Company could detect crop problems be- fore they became visible to the eye. Mounted on a plane flown at 3,000 feet at night, an infra- red scanner measured the heat emitted by crops. The data were transformed into a color-code map showing where plants were running" fevers". Farmers could then spot-spray, using 50 to 70 percent less pesticide than they otherwise would. The bad news is that Paley’s company closed down in 1984, after only three years. Farmers resisted the new technology and long-term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. "This technique can be used on 75 percent of agricultural land in the United States", says George Oerther of Texas A&M. Ray Jackson, who recently retired from the Department of Agricultrue, thinks re- mote infrared crop scanning could be adopted by the end of the decade. But only if Paley finds the financial backing which he failed to obtain 10 years ago. Plants will emit an increased amount of heat when they are ______.
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简述物流企业兼并的动机。
Passage Five The agricultural revolution in the nineteenth century involved two things the invention of labor-saving machinery and the development of scientific agriculture. Labor-saving machinery naturally appeared first where labor was scarce. "In Europe", said Thomas Jefferson," the object is to make the most of their land, labor being abundant; here it is to make the most of our labor, land being abundant." It was in America, therefore, that the great advances in nine-teenth-century agricultural machinery first came. At the opening of the century, with the exception of a crude plow, farmers could have carded practically all of the existing agricultural implements (家具) on their backs; by 1860, most of the machinery in use today had been designed in an early form. The most important of the early inventions was the iron plow. As early as 1790 Charles Newbold of New Jersey had been working on the idea of a cast-iron plow and spent his entire fortune in introducing his invention. The farmers, however, would have none of it, claiming that the iron poisoned the soil and made the weeds grow. Nevertheless, many people devoted their attention to the plow, until in 1869 James Oliver of South Bend, Indiana, turned out the first chilled-steel (冷淬钢) plow. What point is the author making by stating that farmers could carry nearly all their tools on their backs（）
Passage Two Your mind like your body is a thing where the powers are developed by effort. This is a principal use, as I see it, of hard work in studies. Unless you train your body you can’t be a good sportsman, and unless you train your mind you can’t be much of a scholar. The four mi- les a boatman covers at top speed is in itself nothing to the good, but the physical capacity to hold out over the distance is thought to be of some value. So a good part of what you learn by hard study may not be retained forever, and may not seem to be of much final value, but your mind is a better and more powerful instrument because you have learned it. "Knowledge is power," but still more the ability of acquiring and using knowledge is power. If you have a trained and powerful mind, you are bound to have stored it with something, its value is more in what it can do, what it can grasp and use, than in what it contains; and if it were possible, as it is not, to come out of college with a trained mind and nothing useful in it, you would still be ahead, and still, in a manner, educated. The author emphasizes that many of the facts you acquire by hard study （）
Directions: There are five reading Passages in this part. Each passage is followed by five questions. For each question there are four suggested answers marked A, B, C and D. Choose one best answer and blacken the corresponding letter on ANSWER SHEET I.Passage OneSince the early 1980s, scientists have revealed some 40 human genes involved in cancer. These genes are essential for normal growth, but can be subverted to cause a tumor.Dr. Jorge Yunis of the University of Minnesota Medical School in Minneapolis has found that 70 percent of oncogenes, or cancer-causing genes, are located near inherited weak points on chromosomes(染色体). Varying from individual to individual, vulnerable to chemical carcinogens(致癌剂) ,X rays and other cancer-inducing agents."If a chromosome snaps apart in the immediate vicinity of an oncogene," says Yunis, "normal genetic control mechanisms could break down and the stage would be set for the formation of cancer." Younis hag shown that such a sequence occurs at the beginning of numerous leukemias (白血病), lymphomas (淋巴瘤) and some tumors of the lung, colon (结肠) and breast.Yunis and Other investigators have found that petroleum-based products--notably pesticides and insecticides--damage specific sites on at least two of the 23 pairs of human chromosomes that carry genetic information. Similarly, tobacco smoke tends to attack a part of another chromosome. According to the context, the word in "oncogenes" in para. 2 means （）
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