An important new industry, oil refining, grew after the Civil war. Crude oil, or petroleum - a dark, thick ooze from the earth - had been known for hundreds of years, but little use had ever been made of it. In the 1850s Samuel M. Kier, a m...
The theory of plate tectonics describes the motions of the lithosphere, the comparatively rigid outer layer of the Earth that includes all the crust and part of the underlying mantle. The lithosphere is divided into a few dozen plates of va...
Icebergs are among natures most spectacular creations, and yet most people have never seen one. A vague air of mystery envelops them. They come into being ----- somewhere ------in faraway, frigid waters, amid thunderous noise and splashing...
Topaz is a hard, transparent mineral. It is a compound of aluminum, silica, and fluorine. Gem topaz is valuable. Jewelers call this variety of the stone precious topaz. The best-known precious topaz gems range in color from rich yellow to l...
If the salinity of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of the...
Atmospheric pressure can support a column of water up to 10 meters high. But plants can move water much higher; the sequoia tree can pump water to its very top more than 100 meters above the ground. Until the end of the nineteenth century,...
American black bears appear in a variety of colors despite their name. In the eastern part of their range, most of these brown, red, or even yellow coats. To the north, the black bear is actually gray or white in color. Even in the same lit...
1. 学习方法，态度： 229.The best way to learn a new subject or skill is to study small segment s or details in great depth rather than to start by trying to develop a sense of the whole. a) 这两种学习方法在学习种都是很重...
155. Contemporary society offers so many ways of learning that reading books is no longer very important....
2. 学习课程： 80. All students should be required to take courses in the sciences, even if they have no interest in science. 90. College students should be encouraged to pursue subjects that interest them rather than seek programs that...
106 All students should be required to take at least one course in ethics, even if taking the course means a decreased emphasis on academic subjects....
50 In order to improve the quality of instruction at the college and university level, all faculties should be required to spend time working outside the academic world in professions relevant to the courses they teach....
Nowadays, advertising has an extreme importance in our society, as it is ubiquitous and one cannot help but bumping into it. Besides, its techniques are more and more sophisticated, thus appealing people more easily....
British Columbia is the third largest Canadian provinces, both in area and population. It is nearly 1.5 times as large as Texas, and extends 800 miles (1,280km) north from the United States border. It includes Canadas entire west coast and...
Botany, the study of plants, occupies a peculiar position in the history of human knowledge. For many thousands of years it was the one field of awareness about which humans had anything more than the vaguest of insights. It is impossible t...
In the oysters were raised in much the same way as dirt farmers raised tomatoes- by transplanting them. First, farmers selected the oyster bed, cleared the bottom of old shells and other debris, then scattered clean shells about. Next, they...
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By the mid-nineteenth century, the term icebox had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in h...
Scattered through the seas of the world are billions of tons of small plants and animals called plankton. Most of these plants and animals are too small for the human eye to see. They drift about lazily with the currents, providing a basic...
When did sport begin? If sport is, in essence, play, the claim might be made that sport is much older than humankind, for , as we all have observed, the beasts play. Dogs and cats wrestle and play ball games. Fishes and birds dance. The ape...
