51. Using many symbols makes it possible to put a large amount of information on a single map.

　　51.使用多種多樣的符號可以在一張地圖里放進大量的信息。

　　52. Anarchism is a term describing a cluster of doctrines and attitudes whose principal uniting feature is the belief that government is both harmful and unnecessary.

　　52.無政府主義這個詞描述的是一堆理論和態度，它們的主要共同點在于相信政府是有害的，沒有必要的。

　　53. Probably no man had more effect on the daily lives of most people in the Untied States than did Henry Ford a pioneer in automobile production.

　　53.恐怕沒有誰對大多數美國人的日常生活影響能超過汽車生產的先驅亨利.福特。

　　54. The use of well-chosen nonsense words makes possible the testing of many basic hypotheses in the field of language learning.

　　54.使用精心挑選的無意義詞匯，可以檢驗語言學科里許多基本的假定。

　　55. The history of painting is a fascinating chain of events that probably began with the very first pictures ever made.

　　55.優化歷史是由一連串的迷人事件組成，其源頭大概可以上溯到最早的。

　　56. Perfectly matched pearls, strung into a necklace, bring a far higher price than the same pearls told individually.

　　56.相互般配的珍珠，串成一條項鏈，就能賣到比單獨售出好得多的價錢。

　　57. During the eighteenth century, Little Turtle was chief of the Miami tribe whose territory became what is now Indiana and Ohio.

　　57.十八世紀時，小烏龜是邁阿密部落的酋長，該部落的地盤就是今天的印第安那州和俄亥俄州。

　　58. Among almost seven hundred species of bamboo, some are fully grown at less than a foot high, while others can grow three feet in twenty-four hours.

　　58.在竹子的近七百個品種中，有的全長成還不到一英尺，有的卻能在二十四小時內長出三英尺。

　　59. Before staring on a sea voyage, prudent navigators learn the sea charts, study the sailing directions, and memorize lighthouse locations to prepare themselves for any conditions they might encounter.

　　59.謹慎的航海員在出航前，會研究航向，記錄的燈塔的位置，以便對各種可能出現的情況做到有備無患。

　　60. Of all the economically important plants, palms have been the least studied.

　　60.在所有的經濟作物中，棕櫚樹得到的研究最少。

　　61. Buyers and sellers should be aware of new developments in technology can and does affect marketing activities.

　　61.購買者和銷售者都應該留意技術的新發展，原因很簡單，因為技術能夠并且已經影響著營銷活動。

　　62. The application of electronic controls made possible by the microprocessor and computer storage have multiplied the uses of the modern typewriter.

　　62.電腦儲存和由于電子微處理機得以實現的電控運用成倍的增加了現代打字機的功能。

　　63. The human skeleton consists of more than two hundred bones bound together by tough and relatively inelastic connective tissues called ligaments.

　　63.人類骨骼有二百多塊骨頭組成，住些骨頭石油堅韌而相對缺乏彈性的，被稱為韌帶的結蒂組連在一起。

　　64. The pigmentation of a pearl is influenced by the type of oyster in which it develops and by the depth, temperature, and the salt content of the water in which the oyster lives.

　　64.珍珠的色澤受到作為其母體牡蠣種類及牡蠣生活水域的深度，溫度和含鹽度的制約。

　　65. Although mockingbirds superbly mimic the songs and calls of many birds, they can nonetheless be quickly identified as mockingbirds by certain aural clues.

　　65.盡管模仿鳥學很多種鳥的鳴叫聲惟妙惟肖，但人類還是能夠依其聲音上的線索很快識別它們。

　　66. Not only can walking fish live out of water, but they can also travel short distances over land.

　　66.鲇魚不僅可以離開水存活，還可以在岸上短距離移動。

　　67. Scientists do not know why dinosaurs became extinct, but some theories postulate that changers in geography, climate, and sea levels were responsible.

　　67.科學家不知道恐龍為何絕種了，但是一些理論推斷是地理，氣候和海平面的變化造成的。

　　68. The science of horticulture, in which the primary concerns are maximum yield and superior quality, utilizes inFORMation derived from other sciences.

　　68.主要目的在于豐富和優質的農藝學利用了其他科學的知識。

　　69. Snow aids farmers by keeping heart in the lower ground levels, thereby saving the seeds from freezing.

　　69.雪對農民是一種幫助，因為它保持地層土壤的溫度，使種子不致凍死。

　　70. Even though the precise qualities of hero in literary words may vary over time, the basic exemplary function of the hero seems to remain constant.

　　70.歷代文學作品中的英雄本色雖各有千秋，但其昭世功力卻是恒古不變的。

　　71. People in prehistoric times created paints by grinding materials such as plants and clay into power and then adding water.

　　71.史前的人們制造顏料是將植物和泥土等原料磨成粉末，然后加水。

　　72. Often very annoying weeds, goldenrods crowd out less hardy plants and act as hosts to many insect pests.

　　72.黃菊花通常令人生厭，它擠走不那么頑強的植物，并找來很多害蟲。

　　73. Starting around 7000 B.C., and for the next four thousand years, much of the Northern Hemisphere experienced temperatures warmer than at present.

　　73.大約從公元前七千年開始，在四千年當中，北半球的溫度比現在高。

　　74. When Henry Ford first sought financial backing for making cars, the very notion of farmers and clerks owning automobiles was considered ridiculous.

　　74.當亨利.福特最初制造汽車為尋求資金支持時，農民和一般職員也能擁有汽車的想法被認為是可笑的。

　　75. Though once quite large, the population of the bald eagle across North America has drastically declined in the past forty years.

　　75.北美禿頭鷹的數量一度很多，但在近四十年中全北美的禿頭鷹數量急劇下降。

　　76. The beaver chews down trees to get food and material with which to build its home.

　　76.水獺啃倒樹木，以便取食物并獲得造窩的材料。

　　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.

　　77.長卷毛狗曾被用作獵鴨時叼回獵物的獵犬，但是美國Kennel Club卻不承認它們為獵犬，因為它們現在大多數作為寵物飼養。

　　78. As a result of what is now know in physics and chemistry, scientists have been able to make important discoveries in biology and medicine.

　　78.物理學和化學的一個成果是使得科學家們能在生物學和醫學上獲得重大發現。

　　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.

　　79.根據默默無聞的小說制作優秀影片在美國由來已久，已經成為傳統。

　　80. Since the consumer considers the best fruit to be that which is the most attractive, the grower must provide products that satisfy the discerning eye.

　　80.因為顧客認為最好的水果應該看起來也是最漂亮的，所以種植者必須提供能滿足挑剔眼光的產品。

　　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.

　　81.電視，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。

　　82. Television is more than just an electronics; it is a means of expression, as well as a vehicle for communication, and as such becomes a powerful tool for reaching other human beings.

　　82.電視不僅僅是一件電器;它是表達的手段和交流的載體并因此成為聯系他人的有力工具。

　　83. Even more shocking is the fact that the number and rate of imprisonment have more than doubled over the past twenty years, and recidivismthat is the rate for re-arrestis more than 60 percent.

　　83.更讓人吃驚的事實是監禁的數目和比例在過去的二十年中翻了一番還有余，以及累犯率即再次拘押的比例為百分之六十強。

　　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.

　　84.他的教書生涯始于麻省理工學院，但是William Rainey Harper把他吸引到了新成立的芝加哥大學。他在那里正式任職長達整整一代人的時間。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。

　　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 moldy 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.

　　85.樹獺即不講究衛生，以至于它粗糙的毛發上生出綠苔，成群的寄生蛾生長在它的皮毛深處，變成毛毛蟲，并以它的臟毛為食。她的肌肉不能讓他哪怕在很短的距離以內以每小時一公里的速度移動。它能做的最敏捷的動作就是揮一揮它彎曲的胳膊。

　　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.

　　86.人造花卉即可用于科學目的，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。

　　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.在伊利諾州Angonne市的一個廢棄煤礦的三年研究取得了成果，科學家們相信這些成果可以幫助改造把美國產煤區弄得傷痕累累的數千個舊煤場。

　　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.當有關西部鐵路的說服和規劃工作終于完成后，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。

　　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.由于空間不足，藝術博物館在考慮購買和接受捐贈的藝術品是越來越慎重，有些情況下放棄其進一步改善收藏的機會。

　　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.美國憲法要求總統是生于美國本土的公民，三十五歲以上，并且在美國居住了至少十四年。

　　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.美國西部的不毛之地正成為玩耍的地方，對越來越多擁有摩托車或越野單車類車輛的，喜歡放縱于爬坡比賽或開辟新的沙漠通道的尋歡作樂者具有不斷增長的吸引力。

　　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.石頭不會腐爛，所以以前的工具能保存下來，雖然它們的制造者已經消失的無影無蹤。

　　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.昆蟲就將會使我們無法在這個世界上居住;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的禽獸。

　　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.

　　94.確實，他們在探險中遇到了極具威脅性的困難和危險，而他們的裝備會讓一個現代登山者想一想都會渾身顫栗。不過他們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.

　　95.老人和年輕人之間只有一個區別：年輕人的前面有輝煌的未來，老年人燦爛的未來卻已在它們身后。這也許就是困難之所在。

　　96. I find young people exciting. They have an air of freedom, and they have not a dreary commitment to mean ambitions or love comfort. They are not anxious social climbers, and they have no devotion to material things.

　　96.我們位年強人振奮。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。他們不是焦慮的向上爬的人，他們不會對物質性的東西難舍難分。

　　97. I am always amazed when I hear people saying that sport creates goodwill between the nations, and that if only the common peoples of the world could meet one another at football or cricket, they would have no inclination to meet on the battlefield.

　　97.每次我聽說體育運動能夠在國家間建立起友好感情，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場上相遇的話，我都倍感詫異。

　　98. It is impossible to say simply for the fun and exercise: as soon as the question of prestige arises, as soon as you feel that you and some larger unit will be disgraced if you lose, the most savage combative instincts are around.

　　98.沒有可能僅僅為了娛樂或鍛煉而運動：一旦有了問題，一旦你覺得你輸了你和你所屬團體會有失體面時，你最野蠻的好斗本能就會被激發出來。

　　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 echo-location in bats is often compared with radar, the principle of which is similar.