The History and Composition of Laundry Detergent     The earliest ancient people used plain water for cleaning. Water can dissolve different kinds of substances and then...

Classical Greek Tragedy       In 534 B.c.E. the city-state of Athens in what is today Greece added performances of tragedies to its annual festival honoring the go...

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

TF阅读真题第848篇Wool production in Europe on the high Middle Ages

Lenape Horticulture       Older scholarship on Native Americans assumed that, at the time of their first contact with Europeans, Native Americans in the northeaste...

Extraterrestrial lmpact and Megafauna Extinctions     About 13,000 years ago, near the end of a period called the Pleistocene, North America was populated by megafauna (...

Mars's Disappearing Atmosphere   For about the first billion years of its life, Mars was probably a watery planet. There are signs of past water in surface features, such as d...

题目： Carbon Dioxide Levels in the Ocean The concentration of carbon dioxide gas (CO2) is rising in the atmosphere, and some of this CO2 is taken up by ocean surface waters. To ...

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Reconstructing the Spread of the Grain Weevil Perhaps the most common, most widespread, and arguably most destructive pest of stored grain in history is the grain weevil Sitophilu...