Both the steamboat and the railroad system with its steam-powered trains revolutionized transport in the United States in the nineteenth century. Entire regions that would hardly h...

TF阅读真题第774篇Greece Emerges from the Dark Ages

TF阅读真题第773篇Facial Expressions

Underground Water The hydrosphere is the collective mass of water at or near Earth’s surface. Beneath the land surface is the underground water component of the hydrosphere. The ...

TF阅读真题第772篇The Development of Agriculture

Characteristics of Tropical Rain Forests Almost all the action in a rain forest (not just photosynthesis but also flowering, fruiting, predation, and herbivory) happens high in t...

    Economics begins with the assumption that human actions are rational-intended for maximum self-benefit. For example, people pay more for a larger box of the same cer...

The oldest Earth rocks known to date, found in Quebec, Canada in 2008， were determined to be about 4.3 billion years old. However, the oldest known materials of the solar system-M...

There is a much greater similarity between the flowering plant floras of different continents—South America, Africa, Asia, and Australia—than between the mammalian faunas  (anim...

  Personality Traits Trait theory is a major approach to the study of human personality. Trait psychologists are interested in measuring personality traits, which are endurin...