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61. Buyers and sellers should be aware of new developments in technology can and does affect marketing activities. 购买者和销售者都应该留意技术的新发展，原因很简单，因为技术能够并且已经影响着营销活动。

62. The application of electronic controls made possible by the microprocessor and computer storage have multiplied the uses of the modern typewriter. 电脑储存和由于电子微处理机得以实现的电控运用成倍的增加了现代打字机的功能。

63. The human skeleton consists of more than two hundred bones bound together by tough and relatively inelastic connective tissues called ligaments. 人类骨骼有二百多块骨头组成，住些骨头石油坚韧而相对缺乏弹性的，被称为韧带的结蒂组连在一起。

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. 珍珠的色泽受到作为其母体牡蛎种类及牡蛎生活水域的深度，温度和含盐度的制约。

65. Although mockingbirds superbly mimic the songs and calls of many birds, they can nonetheless be quickly identified as mockingbirds by certain aural clues. 尽管模仿鸟学很多种鸟的鸣叫声惟妙惟肖，但人类还是能够依其声音上的线索很快识别它们。

66. Not only can walking fish live out of water, but they can also travel short distances over land. 鲇鱼不仅可以离开水存活，还可以在岸上短距离移动。

67. Scientists do not know why dinosaurs became extinct, but some theories postulate that changers in geography, climate, and sea levels were responsible. 科学家不知道恐龙为何绝种了，但是一些理论推断是地理，气候和海平面的变化造成的。

68. The science of horticulture, in which the primary concerns are maximum yield and superior quality, utilizes information derived from other sciences. 主要目的在于丰富和优质的农艺学利用了其他科学的知识。

69. Snow aids farmers by keeping heart in the lower ground levels, thereby saving the seeds from freezing. 雪对农民是一种帮助，因为它保持地层土壤的温度，使种子不致冻死。

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. 当代文学作品中的英雄本色虽各有千秋，但其昭世功力却是恒古不变的。

71. People in prehistoric times created paints by grinding materials such as plants and clay into power and then adding water. 史前的人们制造颜料是将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. 黄菊花通常令人生厌，它挤走不那么顽强的植物，并找来很多害虫。

73. Starting around 7000 B.C., and for the next four thousand years, much of the Northern Hemisphere experienced temperatures warmer than at present. 大约从公元前七千年开始，在四千年当中，北半球的温度比现在高。

74. When Henry Ford first sought financial backing for making cars, the very notion of farmers and clerks owning automobiles was considered ridiculous. 当亨利.福特初制造汽车为寻求资金支持时，农民和一般职员也能拥有汽车的想法被认为是可笑的。

75. Though once quite large, the population of the bald eagle across North America has drastically declined in the past forty years. 北美秃头鹰的数量一度很多，但在近四十年中全北美的秃头鹰数量急剧下降。

76. The beaver chews down trees to get food and material with which to build its home. 水獭啃倒树木，以便取食物并获得造窝的材料。

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. 长卷毛狗曾被用作猎鸭时叼回猎物的猎犬，但是美国Kennel Club却不承认它们为猎犬，因为它们现在大多数作为宠物饲养。

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. 物理学和化学的一个成果是使得科学家们能在生物学和医学上获得重大发现。

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. 根据默默无闻的小说制作影片在美国由来已久，已经成为传统。

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. 因为顾客认为的水果应该看起来也是漂亮的，所以种植者必须提供能满足挑剔眼光的产品。