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813篇when honeybees become foragers

TF阅读真题第814篇Agriculture in Colonial New England

  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...

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

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 ...

TF阅读真题第834篇Group living

  Sensory Ecology     Some of the most important sensory information animals have to process comes from other animals. Interactions between predators and prey, pare...

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...

TF阅读真题第833篇The Radiocarbon Dating of Prehistoric American Sites