76. The beaver chews down trees to get food and material with which to build its home。

　　76.水獭啃倒树木，以便取食物并获得造窝的材料。

　　77. Poodles were once usedas retrievers in duck hunting, but the American Kennel Club does notconsider them sporting dogs because they are now primarily kept as pets。

　　77.长卷毛狗曾被用作猎鸭时叼回猎物的猎犬，但是美国Kennel Club却不承认它们为猎犬，因为它们现在大多数作为宠物饲养。

　　78. As a result of what isnow know in physics and chemistry, scientists have been able to makeimportant discoveries in biology and medicine。

　　78.物理学和化学的一个成果是使得科学家们能在生物学和医学上获得重大发现。

　　79. The practice of makingexcellent films based on rather obscure novels has been going on solong in the United States as to constitute a tradition。

　　79.根据默默无闻的小说制作优秀影片在美国由来已久，已经成为传统。

　　80. Since the consumerconsiders the best fruit to be that which is the most attractive, thegrower must provide products that satisfy the discerning eye。

　　80.因为顾客认为最好的水果应该看起来也是最漂亮的，所以种植者必须提供能满足挑剔眼光的产品。

　　81. Television the mostpervasive and persuasive of modern technologies, marked by rapid changeand growth, is moving into a new era, an era of extraordinarysophistication and versatility, which promises to reshape our lives andour world。

　　81.电视，这项从迅速变化和成长为标志的最普及和最有影响力的现代技术，正在步入一个新时代，一个极为成熟和多样化的时代，这将重塑我们的生活和世界。

　　82. Television is more thanjust an electronics; it is a means of expression, as well as a vehiclefor communication, and as such becomes a powerful tool for reachingother human beings。

　　82.电视不仅仅是一件电器；它是表达的手段和交流的载体并因此成为联系他人的有力工具。

　　83.Even more shocking is the fact that the number and rate of imprisonmenthave more than doubled over the past twenty years, andrecidivism------that is the rate for re-arrest------is more than 60percent。

　　83.更让人吃惊的事实是监禁的数目和比例在过去的二十年中翻了一番还有余，以及累犯率——即再次拘押的比例——为百分之六十强。

　　84.William Rainey Harperlured him to the new university of Chicago, where he remainedofficially for exactly a generation and where his students in advancedcomposition found him terrifyingly frigid in the classroom butsympathetic and understanding in their personal conferences。

　　84.他的教书生涯始于麻省理工学院，但是William Rainey Harper把他吸引到了新成立的芝加哥大学。他在那里正式任职长达整整一代人的时间。他的高级作文课上的学生觉得他在课上古板得可怕，但私下交流却富有同情和理解。

　　85. The sloth pays suchlittle attention to its personal hygiene that green algae grow on itscoarse hair and communities of a parasitic moth live in the depths ofits coat producing caterpillars which graze on its mouldy hair. Itsmuscles are such that it is quits incapable of moving at a speed ofover a kilometer an hour even over the shortest distances and theswiftest movement it can make is a sweep of its hooked arm。

　　85.树獭即不讲究卫生，以至于它粗糙的毛发上生出绿苔，成群的寄生蛾生长在它的皮毛深处，变成毛毛虫，并以它的脏毛为食。她的肌肉不能让他哪怕在很短的距离以内以每小时一公里的速度移动。它能做的最敏捷的动作就是挥一挥它弯曲的胳膊。

　　86. Artificial flowers areused for scientific as well as for decorative purposes. They are madefrom a variety of materials, such as way and glass, so skillfully thatthey can scarcely be distinguished from natural flowers。

　　86.人造花卉即可用于科学目的，也可用于装饰目的，它们可以用各种各样的材料制成，臂如蜡和玻璃；其制作如此精巧，几乎可以以假乱真。

　　87. Three years of researchat an abandoned coal mine in Argonne, Illinois, have resulted infindings that scientists believe can help reclaim thousands of minedisposal sites that scar the coal-rich regions of the United States。

　　87.在伊利诺州Angonne市的一个废弃煤矿的三年研究取得了成果，科学家们相信这些成果可以帮助改造把美国产煤区弄得伤痕累累的数千个旧煤场。

　　88. When the persuading andthe planning for the western railroads had finally been completed, thereally challenging task remained: the dangerous, sweaty, backbreaking,brawling business of actually building the lines。

　　88.当有关西部铁路的说服和规划工作终于完成后，真正艰难的任务还没有开始；即危险，吃力，需要伤筋动骨和吵吵嚷嚷的建造这些铁路的实际工作。

　　89. Because of the spacecrunch, the Art Museum has become increasingly cautious in consideringacquisitions and donations of art, in some cases passing upopportunities to strengthen is collections。

　　89.由于空间不足，艺术博物馆在考虑购买和接受捐赠的艺术品是越来越慎重，有些情况下放弃其进一步改善收藏的机会。

　　90. The United StatesConstitution requires that President be a natural-born citizen,thirty-five years of age or older, who has lived in the United Statesfor a minimum of fourteen years。

　　90.美国宪法要求总统是生于美国本土的公民，三十五岁以上，并且在美国居住了至少十四年。