The wet rice fields of Asia are the most productive of all preindustrial intensive agricultural systems. As the term 'wet rice' suggests, the method involves flooding the fi...

TF阅读真题第681篇Physiological Adaptations of Tuna

TF阅读真题第678篇Telescopes

题目：   Peruvian farmers have used guano (dried waste of seabirds) as a plant fertilizer since ancient times, but guano was not exported to Europe until 1840. Guano has mu...

题目： Hot Springs and Geysers     Water held in the cracks in rocks and spaces in soil is called groundwater. A hot spring forms when hot groundwater rises through a c...

题目： The Origin of Writing Who invented the first writing? Like many questions of its type in archaeology, this one is not easily answered.Some might argue that the paintings ...

  题目： Endangered Coral Reefs     Reef-building corals are made by polyps (tiny sea animals) that build on the skeletal remains of previous generations provid...

题目：   Planetary scientists have struggled to understand how three rocky planets could have turned out so differently. Why is the atmosphere on Venus 100 times as dense as ...

题目： The Song Dynasty Expansion     About 1,000 years ago, during the Song Dynasty (960-1279), China saw a remarkable period of expansion and prosperity. Among the re...

题目： How Humans Became Food Producers   Present evidence indicates that the earliest plant domestication (the process of adapting wild plants for human use)took place gradu...