The Nile River Valley Though the verdant green course of the Nile Valley appears to be the very antithesis of the bleached Saharan sands through which it flows, these two contras...

Life on Mars Astronomers strongly suspect that Mars currently has no liquid water, diminishing the chances for life there now. But running water and a denser atmosphere in the pas...

Tidal Heating on lo     To understand tidal heating, we must go back to when the twin spacecraft Voyager 1 and Voyager 2 made close flybys of the moon lo, Jupiter's clos...

TF阅读真题第806篇Maya Population in the Classic Period

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Human Responsibility for Megafaunal Extinctions     Paleontologists are intrigued by the question of what caused a diverse group of large animals (megafauna) to become e...

Sources of Prosperity during China's Song Dynasty     In the tenth century. after a period of political fragmentation, China began to enjoy a peaceful and prosperous per...

Britain's Industrialization     The Industrial Revolution was an extended period of economic growth and change brought about by the application of mineral energy and t...

Insect Colony Movement     In general, colonies of social insects such as bees or ants move either to change nesting sites when the current site deteriorates in quality,...

Early Food Production in Africa   Farming appeared in Africa by 5000 B.c.E. Eventually, several different styles of food production developed. These variations were caused by ...