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. 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 and the planning for the western railroads had finally been completed, the really 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 space crunch, the Art Museum has become increasingly cautious in considering acquisitions and donations of art, in some cases passing up opportunities 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 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.
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. Arid regions in the southwestern United States have become increasingly inviting 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.
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. 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.
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. Insects would make it impossible for us to live in the world; they would devour all our crops and kill our flocks and herds, if it were not for the protection we get from insect-eating animals.
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. It is true that during their expl