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。