听力原文：People should get no more than 10 percent of their calories from sugar, experts s

al flaw in the software that could allow attacker to take control of a victim's computer.

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证明人口的增长完全不是一成不变的。若技术革新的成果开始减少，从250到350年前就在西方开通出现的并且目前还在继续的人口迅速增长可能也会放慢。当然，当前的知识革命也许会持续下去而无法预见其未来。无论如何，与那种认为人口以几何级数持续增长的观点相反，从长远的观点来说，人口可望受到生产力的调节。接受了这一观点，人口的增长就右以被看成是经济进步和人类胜利的标志，而不是社会衰败的标志。

ish primary and secondary schools, for example, the teacher is the primary provider of required information and rote learning plays an important role in the acquisition of this information. British school leavers who then proceed to university face a new set of academic norms and expectations. Although memorization is still required, far greater emphasis is placed on the critical evaluation of received information.

eing and experiencing new things. Traveling, of course, has now become a highly organize business. There are cars and splendid roads, express trains, huge ships and jet airliners, all of which provide us with comforts and security. Scientists have also invented machines that can explore outer space. Eventually there will be cheap day excursions to the moon and honeymoon on Venus. People will be able to travel from one planet to another by a space shuttle.

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g them within the reach of all those people who could not afford them in the past.

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ider what we know about it. The words of a language can be listed in a dictionary, but not all the sentences.

pose is to get the students from the same countries together, so we won't get too homesick and can help each other.

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the middle of the street while looking for a certain home or landmark. Other drivers will suddenly slow down at a crossroad to make a right or left turn. Still others never wait for their turns in bottleneck situations where the cars in two lanes must merge alternatively into one. Perhaps the most inconsiderate drivers are those who throw trash out their windows, which spoils the pleasure of driving as well as the environment.

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ughout the world. Such a language would help promote understanding and better feeling among nations. A universal language also would increase cultural and economic ties among various countries.

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and 17 have one or more learning disabilities. Early diagnosis and treatment are important because specialized teaching techniques can help many of these students overcome their disability and succeed in school.

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