Animal Farming in the Chesapeake Colonies The Chesapeake colonies were established by English settlers near Chesapeake Bay in North America in the seventeenth century. Tobacco pr...

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...

The Key Factors Influencing Soil Formation   Soil is the product of the complex interplay of several factors. Weathering, a process that breaks down rocks by physical (mechani...

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...

Dutch Art and the Middle Class     Throughout history,the wealthy have been the most avid art collectors. Indeed, the money necessary to commission leading artists to ...

  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...

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

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...

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 (...

American Licensing Laws 题目：   In the early-nineteenth-century United States, the medical profession was largely unregulated. There were several competing schools of medic...