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
imprisonment have more than doubled over the past twenty years, and
recidivism------that is the rate for re-arrest------is more than 60
percent. 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。
7 传说中的100句背7000单词
84. His teaching began at the Massachusetts Institute of Technology,
but William Rainey Harper lured him to the new university of Chicago,
where he remained officially for exactly a generation and where his
students in advanced composition found him terrifyingly frigid in the
classroom but sympathetic and understanding in their personal
conferences. 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 such little attention to its personal
hygiene
that green algae grow on its coarse hair and communities of a parasitic
moth live in the depths of its coat producing caterpillars which graze
on its mouldy hair. Its muscles are such that it is quits incapable 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. 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 are used for scientific as well as for
decorative purposes. They are made from a variety of materials, such as
way and glass, so skillfully that they can scarcely be distinguished
from natural flowers. 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 research at an abandoned coal mine in Argonne,
Illinois, have resulted in findings that scientists believe can help
reclaim thousands of mine disposal sites that scar the coal-rich regions
of the United States. 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 and the planning for the western railroads
had finally been completed, the really challenging task remained: the
dangerous, sweaty, backbreaking, brawling business of