How Did Life Begin For life to begin, it needed the right sorts of molecules, some sort of energy(such as that created by lightning), and the right environment-perhaps the 'warm l...

Diving for Food by Birds     Seabirds are physiologically adapted to dive underwater for food, a strategy that necessarily poses problems. An obvious problem is that whe...

Were Dinosaurs Endothermic   题目： Because dinosaurs are considered reptiles, they were for many years thought to be cold-blooded (ectothermic) like modern reptiles, requiri...

Language and Migration 题目： The study of language can offer important clues about the historic migration of people around the world. Most historians would place the emergence o...

  Archaeoptertx and Flight 题目： It is not known whether Archaeopteryx, the earliest birdlike creature for which fossils have been found, could fly-but it probably did, at ...

  Agricultural Practices of the Maya   题目：     The Maya civilization flourished for centuries on the Yucatan Peninsula and other areas of Mesoamerica, reac...

Deer Antlers and Seasonal Mating 题目：   In temperate (moderate)climates and subpolar regions (those nearer to the poles), where winters are usually long and the vegetation ...

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...

TF阅读真题第696篇The Northern Long-necked Turtle

    题目： Transportation and Economic Change in the Nineteenth-Century       Between 1820 and 1860,the American economy entered a new stage of develop...