74. What are the two ways thieves sell the stolen cars?
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　　75. What type of security system can help the police track down a stolen car?
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　　 21.What brought about the decline in the demand for American farm products?
　　 A) The impact of the Great Depression.
　　 B) The shrinking of overseas markets.
　　 C) The destruction caused by the First World War.
　　 D) The increased exports of European countries.
　　 22.The chief concern of the American government in the area of agriculture in the 1920s was ______.
　　 A) to increase farm production
　　 B) to establish agricultural laws
　　 C) to prevent farmers from going bankrupt
　　 D) to promote the mechanization of agriculture
　　 23.The Agricultural Adjustment Act encouraged American farmers to ______.
　　 A) reduce their scale of production
　　 B) make full use of their land
　　 C) adjust the prices of their farm products
　　 D) be self-sufficient in agricultural production
　　 24.The Supreme Court rejected the Agricultural Adjustment Act because it believed that the Act ______.
　　 A) might cause greater scarcity of farm products
　　 B) didn’t give the Secretary of Agriculture enough power
　　 C) would benefit neither the government nor the farmers
　　 D) benefited one group of citizens at the expense of others
　　 25.It was claimed that the new laws passed during the Roosevelt Administration were aimed at ______.
　　 A) reducing the cost of farming
　　 B) conserving soil in the long-term interest of the nation
　　 C) lowering the burden of farmers
　　 D) helping farmers without shifling the burden onto other taxpayers
　　 In the 1920s demand for American farm products fell, as European countries began to recover from World War I and instituted austerity (紧缩) programs to reduce their imports. The result was a sharp drop in farm prices. This period was more disastrous for farmers than earlier times had been, because farmers were no longer self-sufficient. They were paying for machinery, seed, and fertilizer, and they were also buying consumer goods. The prices of the items farmers bought remained constant, while prices they received for their products fell. These developments were made worse by the Great Depression, which began in 1929 and extended throughout the 1939s.
　　 In 1929, under President Herbert Hoover, the Federal Farm Board was organized. It established the principle of direct interference with supply and demand, and it represented the first national commitment to provide greater economic stability for farmers.
　　President Hoover’s successor attached even more importance to this problem.
　　One of the first measures proposed by President Franklin D. Roosevelt when he took office in 1933 was the Agricultural Adjustment Act, which was subsequently passed by Congress. This law gave the Secretary of Agriculture the power to reduce production through voluntary agreements with farmers who were paid to take their land out of use. A deliberate scarcity of farm products was planned in an effort to raise prices. This law was declared unconstitutional by the Supreme Court on the grounds that general taxes were being collected to pay one special group of people. However, new laws were passed immediately that achieved the same result of resting soil and providing flood-control measures, but which were based on the principle of soil conservation. The Roosevelt Administration believed that rebuilding the nation’s soil was in the national interest and was not simply a plan to help farmers at the expense of other citizens. Later the government guaranteed loans to farmers so that they could buy farm machinery, hybrid (杂交) grain, and fertilizers.
　　 26.The author says that the powerful computers of today ______.
　　 A) are capable of reliably recognizing the shape of an object
　　 B) are close to exhibiting humanlike behavior
　　 C) are not very different in their performance from those of the 50’s
　　 D) still cannot communicate with people in a human language
　　27.The new trend in artificial intelligence research stems from ______.
　　 A) the shift of the focus of study on to the recognition of the shapes of objects
　　 B) the belief that human intelligence cannot be duplicated with logical, step-by-step programs
　　 C) the aspirations of scientists to duplicate the intelligence of a ten-month-old child
　　 D) the efforts made by scientists in the study of the similarities between transistors and brain cells
　　28.Conrad and his group of AI researchers have been making enormous efforts to ______.
　　 A) find a roundabout way to design powerful computers
　　 B) build a computer using a clever network of switches
　　 C) find out how intelligence developed in nature
　　 D) separate the highest and most abstract levels of thought
　　29.What’s the author’s opinion about the new AI movement?
　　 A) It has created a sensation among artificial intelligence researchers but will soon die out.
　　 B) It’s a breakthrough in duplicating human thought processes.
　　 C) It’s more like a peculiar game rather than a real scientific effort.
　　 D) It may prove to be in the right direction though nobody is sure of its future prospects.
　　30.Which of the following is closest in meaning to the phrase "the only game in town" (Line 3, Para. 4)?
　　 A) The only approach to building an artificially intelligent computer.
　　 B) The only way for them to win a prize in artificial intelligence research.
　　 C) The only area worth studying in computer science.
　　 D) The only game they would like to play in town.
　　 In the 1950s, the pioneers of artificial intelligence (AI) predicted that, by the end of this century, computers would be conversing with us at work and robots would be performing our housework. But as useful as computers are, they’re nowhere close to