Benefits of Migration Why do animals migrate? One obvious answer is to escape cold weather by moving to a warmer region. Each fall, millions of monarch butterflies migrate southw...

题目： Farming in Uruk   The ancient city of Uruk in the southern region of Sumer in the ancient Middle East developed an agricultural system that depended on irrigation to ...

题目： Magma   Magma is a mixture of molten (melted)and semi-molten rock and other solids found beneath Earth's surface.Melting in Earth requires very specific conditions:the...

题目： Day Length and Reproductive Timing in Animals For many animals, producing offspring at a time of year when a maximum amount of food is available is essential. Producing yo...

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

The Greek City-States: Sparta and Athens Of the hundreds of city-states that evolved during the Archaic Age, (800- 479 B.C.), Sparta and Athens stand out for their vividly contras...

The Azolla Event     During the early Eocene period, about 56 million years ago, Earth's atmosphere had high levels of carbon dioxide(CO2) which warmed the planet. But a...

The American Hospital     Few institutions have undergone as radical a transformation as the hospital has in its modern history. It is perhaps distinctive among social i...

TF阅读真题第851篇The Rise and Spread of Japanese Woodblock Prints

TF阅读真题第787篇Moonquake