the definition of price Prices determine how resources are to be used. They are also the means by which products and services that are in limited supply are rationed among buyers. The price system of the United States is a complex network composed o

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高级听力练习

高级听力练习06

Television 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

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高级听力练习

高级听力练习07

Andrew Carnegie Andrew Carnegie, known as the King of Steel, built the steel industry in the United States , and , in the process, became one of the wealthiest men in America . His success resulted in part from his ability to sell the product and in

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高级听力练习

高级听力练习10

Types of Speech Standard usage includes those words and expressions understood, used, and accepted by a majority of the speakers of a language in any situation regardless of the level of formality. As such, these words and expressions are well defin

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高级听力练习

高级听力练习01

A painter hangs his or her finished pictures on a wall, and everyone can see it. A composer writes a work, but no one can hear it until it is performed. Professional singers and players have great responsibilities, for the composer is utterly depend

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高级听力练习11

Archaeology Archaeology is a source of history, not just a bumble auxiliary discipline. Archaeological data are historical documents in their own right, not mere illustrations to written texts, Just as much as any other historian, an archaeologist s

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高级听力练习04

electricity The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flic

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高级听力练习

高级听力练习12

Museums From Boston to Los Angeles, from New York City to Chicago to Dallas, museums are either planning, building, or wrapping up wholesale expansion programs. These programs already have radically altered facades and floor plans or are expected to

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高级听力练习

高级听力练习09

Suburbanization If by suburb is meant an urban margin that grows more rapidly than its already developed interior, the process of suburbanization began during the emergence of the industrial city in the second quarter of the nineteenth century. Befo

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高级听力练习

Earth and Sky:Raindrops 雨滴

Raindrops 雨滴 From a light rain to a heavy downpour, raindrops fall to Earth's surface. And if you watch over time, you'll see that some raindrops are small and some much larger. Find out why -- on today's Earth and Sky. DB: This is Earth and Sky,

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(科普英语)Earth and Sky

Earth and Sky:Politics of CO2 二氧化碳的影响

Politics of CO2 二氧化碳的影响 Mention global warming to a room full of politicians, and you might just start an argument. But one thing most everyone can agree on is the need for more research. Learn more about the next phase of climate study -- to

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(科普英语)Earth and Sky

Earth and Sky;September Equinox 秋分

September Equinox 秋分 We have an equinox because an imaginary plane extending outward from Earth's equator isn't the same as the plane of Earth's orbit around the sun. Learn more about today's equinox -- on Earth and Sky.. JB: This is Earth and Sky

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(科普英语)Earth and Sky

Earth and Sky:Acid Rain 酸雨

Acid Rain 酸雨 Damage from acid rain is widespread - not just in eastern North America, but throughout Europe, Japan, China, and Southeast Asia. Is the rain that's falling on your umbrella acidic? A listener's question -- on today's Earth and Sky. J

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(科普英语)Earth and Sky

Earth and Sky:Aqua Spacecraft 水资源监测太空船

Aqua Spacecraft 水资源监测太空船 NASA's latest and most ambitious weather satellite is measuring Earth's water cycle. Learn more about the Aqua satellite -- today on Earth and Sky. DB: I'm Deborah Byrd. JB: And I'm Joel Block for Earth and Sky. This

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(科普英语)Earth and Sky

Earth and Sky:Spider Widows 蜘蛛寡妇

Spider Widows 蜘蛛寡妇 Spiders give many of us the shivers, though they usually leave people alone. Sometimes these spectacular predators instead prey on each other. Learn more about when spiders serve themselves as dinner -- today on Earth and Sky.

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(科普英语)Earth and Sky

Earth and Sky:Amazon Trends 亚马逊河流域

Amazon Trends 亚马逊河流域 More than 1/3 of Earth's species -- and about 30% of the total living plants and animals on Earth -- live in the Amazon. Discover a noted scientist's perspective on the perils and promise of this region -- today on Earth a

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(科普英语)Earth and Sky

Earth and Sky:Plants vs. Insects 植物和昆虫

Plants vs. Insects 植物和昆虫 New research is shedding light on one of the longest running battles of all time -- the war between plants and insects. Plants may seem helpless, but they have complex chemical defenses. Plants vs. insects -- today on E

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(科普英语)Earth and Sky

Earth and Sky:Water Cycle 水循环

Water Cycle 水循环 All the oceans on earth are salty, while inland water is typically fresh. How does water become salty? We'll answer a listener's question -- today on Earth and Sky. DB: This is Earth and Sky. We recently visited the Austin Childr

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(科普英语)Earth and Sky

Earth and Sky:Narrowing Uncertainties 新发现

Narrowing Uncertainties 新发现 In science, theories abound. Some are proven true, some are modified, some are completely abandoned. But even discrediting a theory is progress. Learn more about sorting through the uncertainties -- on today's Earth an

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(科普英语)Earth and Sky

Earth and Sky:Black and White　黑与白

Black and White黑与白 Sometimes you hear it said that white is a combination of all the colors of the rainbow -- and that black is the absence of color. Find out more about whether black and white are colors -- today on Earth and Sky. JB: This is Ear

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(科普英语)Earth and Sky