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TF阅读真题第909篇The History and Composition of Laundry Detergent
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...
TF阅读真题第897篇How Fossils Map the Past
How Fossils Map the Past Only a tiny fraction of the organisms that have lived during the geologic past have been preserved as fossils.Normally the remains of an ani...
TF阅读真题第887篇Why Did Agriculture Arise
Why Did Agriculture Arise Sometime around 10,000 years ago, some hunter-gatherers took up agriculture. Though the advantages may seem obvious, there are also disadvantages: ...
TF阅读真题第952篇Transportation and Economic Change in the Nineteenth-Century
题目： Transportation and Economic Change in the Nineteenth-Century Between 1820 and 1860,the American economy entered a new stage of develop...
TF阅读真题第926篇Sunspot Cycles
Sunspot Cycles Dark regions on the Sun, called sunspots, were studied in 1610 by Galileo, who turned the newly invented telescope on objects in the sky. A lively deba...
