81. Television the most pervasive¹ and persuasive² of modern technologies, marked by rapid change and growth, is movingsintosa new era, an era of extraordinary sophistication and versatility³, which promises to reshape our lives and our world.

82. Television is more than just an electronics; it is a means of expression, as well as a vehicle for communication, and as such becomes a powerful tool for reaching other human beings.

83. Even more shocking is the fact that the number and rate of imprisonment⁴ have more than doubled over the past twenty years, and recidivism------that is the rate for rearrest------is more than 60 percent.

84. His teaching began at the Massachusetts Institute of Technology, but William Rainey Harper lured⁵ him to the new university of Chicago,swhereshe remained officially for exactly a generation andswhereshis students in advanced composition found him terrifyingly frigid⁶ in the classroom but sympathetic and understanding in their personal conferences.

85. The sloth⁷ pays such little attention to its personal hygiene⁸ that green algae⁹ grow on its coarse hair and communities of a parasitic¹⁰ moth¹¹ live in the depths of its coat producing caterpillars¹² which graze on its mouldy hair. Its muscles are such that it is quits incapable¹³ of moving at a speed of over a kilometer an hour even over the shortest distances and the swiftest movement it can make is a sweep of its hooked arm.

86. Artificial flowers are used for scientific as well as for decorative¹⁴ purposes. They are made from a variety of materials, such as way and glass, so skillfully that they can scarcely be distinguished¹⁵ from natural flowers.

87. Three years of research at an abandoned coal mine in Argonne, Illinois, have resulted in findings that scientists believe can help reclaim¹⁶ thousands of mine disposal sites that scar the coal-richregions of the United States.

88. When the persuading and the planning for the western railroads had finally been completed, the really challenging task remained: the dangerous, sweaty, backbreaking, brawling¹⁷ business of actually building the lines.

89. Because of the space crunch¹⁸, the Art Museum has become increasingly cautious in considering acquisitions and donations of art, in some cases passing up opportunities to strengthen is collections.

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

91. Arid¹⁹ regions in the southwestern United States have become increasingly inviting²⁰ playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in caving new trails in the desert.

92. Stone does decay, and so tools of long ago have remained when even the bones of the man who made them have disappeared without trace.

93. Insects would make it impossible for us to live in the world; they would devour²¹ all our crops and kill our flocks and herds²², if it were not for the protection we get from insect-eating animals.

94. It is true that during their explorations they often faced difficulties and dangers of the most perilous²³ nature, equipped in a manner which would make a modern climber shudder²⁴ at the thought, but they did not go out of their way to court such excitement.

95. There is only one difference between an old man and a young one: the young man has a glorious future before him and old one has a splendid future behind him: and maybe that isswheresthe rub is.

96. I find young people exciting. They have an air of freedom, and they have not a dreary²⁵ commitment to mean ambitions or love comfort. They are not anxious social climbers, and they have no devotion to material things.

97. I am always amazed when I hear people saying that sport creates goodwill²⁶ between the nations, and that if only the common peoples of the world could meet one another at football or cricket, they would have no inclination²⁷ to meet on the battlefield.

98. It is impossible to say simply for the fun and exercise: as soon as the question of prestige arises, as soon as you feel that you and some larger unit will be disgraced if you lose, the most savage²⁸ combative²⁹ instincts are around.

99. It has been found that certain bats emit squeaks³⁰ and by receiving the echoes, they can locate and steer³¹ clear of obstacles------or locate flying insects on which they feed. This echo-location in bats is often compared with radar³², the principle of which is similar.

100. As the time and cost of making a clip drop to a few days and a few hundred dollars, engineers may soon be free to let their imaginations soar without being penalized³³ by expensive failure.

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.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.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.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.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.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.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.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.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.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。

91.美国西部的不毛之地正成为玩耍的地方，对越来越多拥有摩托车或越野单车类车辆的，喜欢放纵于爬坡比赛或开辟新的沙漠通道的寻欢作乐者具有不断增长的吸引力。

92.石头不会腐烂，所以以前的(石器)工具能保存下来，虽然它们的制造者已经消失的无影无踪。

93.昆虫就将会使我们无法在这个世界上居住；如果我们没有受到以昆虫为食的动物的保护，昆虫就会吞嚼掉我们所有的庄稼并杀死我们饲养的禽兽。

94.确实，他们在探险中遇到了极具威胁性的困难和危险，而他们的装备会让一个现代登山者想一想都会浑身颤栗。不过他们并不是刻意去追求刺激的。

95.老人和年轻人之间只有一个区别：年轻人的前面有辉煌的未来，老年人灿烂的未来却已在它们身后。这也许就是困难之所在。

96.我们位年强人振奋。它们带有自由的气息，他们不会为狭隘的野心和贪婪享受而孜孜以求。他们不是焦虑的向上爬的人，他们不会对物质性的东西难舍难分。

97.每次我听说体育运动能够在国家间建立起友好感情，说世界各地的普通人只要能在足球场或板球场上相遇就会没有兴趣在战场上相遇的话，我都倍感诧异。

98.没有可能仅仅为了娱乐或锻炼而运动：一旦有了问题，一旦你觉得你输了你和你所属团体会有失体面时，你最野蛮的好斗本能就会被激发出来。

99.人们已经发现，某些蝙蝠发出尖叫声并靠接受回响来锁定和避免障碍物——或者找到它们赖以为生的昆虫。蝙蝠这种回响定位法常拿来和原理与之很相近似的雷达相比。

100.随着芯片制造时间和费用降低到了几天和几百美元，工程师们可能很快可以任他们的想象驰骋而不会被昂贵的失败所惩罚。