新东方优美背诵短文50篇 Unit35:Oil Refining
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 manufacturer i
新东方优美背诵短文50篇 Unit36:Plate Tectonics and Sea-floor Spreading
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(n.[地]岩石圈)is divided into a few dozen plates o
新东方优美背诵短文50篇 Unit37:Icebergs
37 Icebergs 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 splashi
新东方优美背诵短文50篇 Unit38:Topaz
38 Topaz 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
新东方优美背诵短文50篇 Unit39:The Salinity of Ocean Waters
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 these is the
新东方优美背诵短文50篇 Unit40:Cohesion-tension Theory
40 Cohesion-tension Theory 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 ni
新东方优美背诵短文50篇 Unit41:American Black Bears
41.American black bears 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
新东方优美背诵短文50篇 Unit42:Coal-fired power plants
42.Coal-fired power plants The invention of the incandescent light bulb by Thomas A. Edison in 1879 created a demand for a cheap, readily available fuel with which to generate large amounts of electric power. Coal seemed to fit the bill, and it fuel
新东方优美背诵短文50篇 Unit43:Statistics
43.Statistics There were two widely divergent influences on the early development of statistical methods. Statistics had a mother who was dedicated to keeping orderly records of government units (states and statistics come from the same Latin root s
新东方优美背诵短文50篇 Unit44:Obtaining Fresh water from icebergs
44.Obtaining Fresh water from icebergs The concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being con
新东方优美背诵短文50篇 Unit45:The Source of Energe
45.The source of Energy A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Suns very center. It is here that is to be found the source of the energy that the Sun constantly pours out i
新东方优美背诵短文50篇 Unit46:Vision
46.Vision Human vision like that of other primates has evolved in an arboreal environment. In the dense complex world of a tropical forest, it is more important to see well that to develop an acute sense of smell. In the course of evolution members
新东方优美背诵短文50篇 Unit47:Folk Culture
A folk culture is a small isolated, cohesive, conservative, nearly self-sufficient group that is homogeneous in custom and race with a strong family or clan structure and highly developed rituals. Order is maintained through sanctions based in the r
新东方优美背诵短文50篇 Unit48:Bacteria
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. Rod-shaped bacteria are u
新东方优美背诵短文50篇 Unit49:Sleep
Sleet is part of a persons daily activity cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper, your sleep cycle is as follows. When you fist drift off into slumber, your eyes will roll abou
