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圖畫。

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。