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.谨慎的航海员在出航前，会研究航向，记录的灯塔的位置，以便对各种可能出现的情况做到有备无患。
60. Of all the economically important plants, palms have been the least studied.
60.在所有的经济作物中，棕榈树得到的研究最少。
61. Buyers and sellers should be aware of new developments in technology can and does affect marketing activities.
61.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.
62.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.
63.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.
64.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.
65.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.
66.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.
67.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.
68.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.
69.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.
70.历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.
71.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.
72.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。 liuxuepaper.com