71. People in prehistoric times created paints by grinding materials such as plants and clay into power and then adding water.
72. Often very annoying weeds, goldenrods crowd out less hardy plants and act as hosts to many insect pests.
73. Starting around 7000 B.C., and for the next four thousand years, much of the Northern Hemisphere experienced temperatures warmer than at present.
74. When Henry Ford first sought financial backing for making cars, the very notion of farmers and clerks owning automobiles was considered ridiculous.
75. Though once quite large, the population of the bald eagle across North America has drastically declined in the past forty years.
76. The beaver chews down trees to get food and material with which to build its home.
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.
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.
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.
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.
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.
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.
83. Even more shocking is the fact that the number and rate of imprisonment have more than doubled over the past twenty years, and recidivism------that is the rate for re-arrest------is more than 60 percent.
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.
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 mouldy 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
99. It has been found that certain bats emit squeaks and by receiving the echoes, they can locate and steer clear of obstacles------or locate flying insects on which they feed. This echo-location in bats is often compared with radar, the principle of which is similar.
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.
13.理论在本质上是对认识了的现实的一种抽象和符号化的表达。
14.儿童在能说或能听懂语言之前，很久就会通过面部表情和靠发出噪声来与人交流了。
15.受当代灌溉(技术设施)之赐，农作物在原来只有仙人掌和荞属科植物才能生存的地方旺盛的生长。
16.机械计时器的发展促使人们寻求更精确的日晷，以便校准机械计时器。
17.人类学是一门科学，因为人类学家采用一整套强有力的方法和技术来记录观测结果，而这样记录下来的观测结果是供他人核查的。
18.真菌在腐化过程中十分重要，而腐化过程将化学物质回馈于土壤，提高其肥力，并分解动物粪便。
19.音叉被敲击时，产生几乎纯质的音调，其音量经久不衰。
20.虽然美洲山河桃树最集中于美国的东南部但是在北至俄亥俄州及伊利诺州也能看见它们。
21.用怪罪别人的办法来解决问题通常被称为寻找替罪羊。
22.一个国家的主要食物是什么，大体取决于什么作物在其天气和土壤条件下生长得最好。
23.在大量的实验中，某一事件发生的几率等于它不发生的几率。
24.大多数物质遇冷收缩，所以他们的密度在固态时高于液态。
25.大脑细胞储存记忆的机理并不为人明白。
26.到了二十一世纪中叶，美国画家和雕塑家开始在世界范围内对艺术产生重大影响。
27.伊丽莎白市，一个重要的航运和制造业中心，坐落于新泽西州的东部。
28. Elizabeth Blackwell，美国第一个女医生，创建了员工一直为女性纽约诊所。
29. Alexander Graham Bell曾告诉家人，他更愿意让后人记住他是聋子的老师，而非电话的发明者。
30.采摘下的迷迭香树叶常绿不衰，因此人们把迷迭香树与怀念联系在一起。
31.骨头看起来是脆硬的，但它也有一定的弹性，使得骨骼能够承受相当的打击。
32.科学家曾相信：氙气是不能形成化合物的。
33.对风暴动力学的研究是为了提高风暴预测从而减少损失，避免人员伤亡。
34.消除通货膨胀应确保还贷的钱应与所贷款的价值相同。
35.未来主义，二十世纪早期的一个艺术思潮。拒绝一切传统，试图通过强调机械和动态来美化生活。
36. Everglades是美国境内最为荒凉和人迹罕至的地区之一，此处有大量的野生动植物而且大多受(法律)保护。
37. Lucretia Mott’s的影响巨大，所以一些权威部门认定她为美国女权运动的创始人。
38.国际市场研究者的活动范围常常较国内市场研究者广阔。
39.大陆分水岭是指北美洛矶山脉上的一道想象线，该线把大西洋流域和太平洋流域区分开来。
40.对地球引力的研究表明，在不寻常的负荷之下地壳和地幔会发生位移。
41.尤它州制造业的年产值大于其工业和农业的总和。
42.墙花之所以叫墙花，是因为其脆弱的枝干经常要靠墙壁或顺石崖生长，以便有所依附。
43.社会心理学的主要焦点是人与人之间的交往，而不是他们各自生活中的事件。
44.给美国的新移民增加教育设施比任何社会运动都更多的激发了Elizabeth Williams的热情。
45.典型的鹌鹑都长有短而圆的翅膀，凭此他们可以在受惊时一跃而起，飞离它们的躲藏地。
46.根据人类学家的说法，直立行走的人的鼻祖面部轮廓与黑猩猩相似，额头后倾，眉毛突出。
47.直到1866年第一条横跨大西洋的电缆才完全成功的架通。
48. John Crowe Ransom在他的著作中描述了他认为是由科学技术给社会带来的精神贫困。
49.父母的教导如果坚定，始终如一和理性，孩子就有可能充满自信。
50.北美远古的Hopewell人很可能种植了玉米和其他农作物，但打猎和采集对他们的经济贸易仍是至关重要的。
51.使用多种多样的符号可以在一张地图里放进大量的信息。
52.无政府主义这个词描述的是一堆理论和态度，它们的主要共同点在于相信政府是有害的，没有必要的。
53.恐怕没有谁对大多数美国人的日常生活影响能超过汽车生产的先驱亨利.福特。
54.使用精心挑选的无意义词汇，可以检验语言学科里许多基本的假定。
55.优化历史是由一连串的迷人事件组成，其源头大概可以上溯到最早的图画。
56.相互般配的珍珠，串成一条项链，就能卖到比单独售出好得多的价钱。
57.十八世纪时，“小乌龟”是迈阿密部落的酋长，该部落的地盘就是今天的印第安那州和俄亥俄州。
58.在竹子的近七百个品种中，有的全长成还不到一英尺，有的却能在二十四小时内长出三英尺。
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.在所有的经济作物中，棕榈树得到的研究最少。
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.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.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.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.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.鲇鱼不仅可以离开水存活，还可以在岸上短距离移动。
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.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.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.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。
