actually building
the lines. 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. 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. 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.
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.
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. 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 explorations they often faced
difficulties and dangers of the most perilous nature, equipped in a
manner which would make a modern climber shudder at the thought, but
they did not go out of their way to court such excitement. 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. 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 is where the rub is. 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. I find young people exciting. They have an air of freedom, and