【正文】 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 penalized by expensive failure. ，工程師們可能很快可以任他們的想象馳騁而不會被昂貴的失敗所懲罰。 99. It has been found that certain bats emit squeaks and by receiving the echoes, they can locate and steer clear of obstaclesor locate flying insects on which they feed. This echolocation in bats is often pared with radar, the principle of which is similar. ，某些蝙蝠發(fā)出尖叫聲并靠接受回響來鎖定和避免障礙物——或者找到它們賴以為生的昆蟲。 97. I am always amazed when I hear people saying that sport creates goodwill between the nations, and that if only the mon peoples of the world could meet one another at football or cricket, they would have no inclination to meet on the battlefield. ，說世界各地的普通人只要能在足球場或板球場上相遇就會沒有興趣在戰(zhàn)場上相遇的話，我都倍感詫異。它們帶有自由的氣息，他們不會為狹隘的野心和貪婪享受而孜孜以求。這也許就是困難之所在。不過他們并不是刻意去追求刺激的。 they would devour all our crops and kill our flocks and herds, if it were not for the protection we get from insecteating animals. ；如果我們沒有受到以昆蟲為食的動物的保護，昆蟲就會吞嚼掉我們所有的莊稼并殺死我們飼養(yǎng)的禽獸。 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. ，所以以前的(石器)工具能保存下來，雖然它們的制造者已經(jīng)消失的無影無蹤。 90. The United States Constitution requires that President be a naturalborn citizen, thirtyfive years of age or older, who has lived in the United States for a minimum of fourteen years. ，三十五歲以上，并且在美國居住了至少十四年。 88. When the persuading and the planning for the western railroads had finally been pleted, the really challenging task remained: the dangerous, sweaty, backbreaking, brawling business of actually building the lines. ，真正艱難的任務還沒有開始；即危險，吃力，需要傷筋動骨和吵吵嚷嚷的建造這些鐵路的實際工作。 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. ，也可用于裝飾目的，它們可以用各種各樣的材料制成，臂如蠟和玻璃；其制作如此精巧，幾乎可以以假亂真。她的肌肉不能讓他哪怕在很短的距離以內(nèi)以每小時一公里的速度移動。他的高級作文課上的學生覺得他在課上古板得可怕，但私下交流卻富有同情和理解。 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 position found him terrifyingly frigid in the classroom but sympathetic and understanding in their personal conferences. ，但是William Rainey Harper把他吸引到了新成立的芝加哥大學。 it is a means of expression, as well as a vehicle for munication, and as such bees a powerful tool for reaching other human beings. ；它是表達的手段和交流的載體并因此成為聯(lián)系他人的有力工具。，這項從迅速變化和成長為標志的最普及和最有影響力的現(xiàn)代技術，正在步入一個新時代，一個極為成熟和多樣化的時代，這將重塑我們的生活和世界。 81. Television the most pervasive and persuasive of modern technologies, marked by rapid change and growth, is moving into a new era, an era of extraordinary sophistication and versatility, which promises to reshape our lives and our world. 79. The practice of making excellent films based on rather obscure novels has been going on so long in the United States as to constitute a tradition. ，已經(jīng)成為傳統(tǒng)。77. Poodles were once used as retrievers in duck hunting, but the American Kennel Club does not consider them sporting dogs because they are now primarily kept as pets. ，但是美國Kennel Club卻不承認它們?yōu)楂C犬，因為它們現(xiàn)在大多數(shù)作為寵物飼養(yǎng)。 75. Though once quite large, the population of the bald eagle across North America has drastically declined in the past forty years. ，但在近四十年中全北美的禿頭鷹數(shù)量急劇下降。 73. Starting around 7000 ., and for the next four thousand years, much of the Northern Hemisphere experienced temperatures warmer than at present. ，在四千年當中，北半球的溫度比現(xiàn)在高。71. People in prehistoric times cr