第613篇POLITICAL SYSTEMS OF THE TWENTIETH CENTURY

TF阅读真题第645篇Seasonal Bird Populations

002Attempts at Determining Earth s Age讲解

034Distribution of Seaweeds讲解

066How Plants and Animals Arrived in the Hawaiian Islands讲解

098Sea Turtle Hatchling Strategies for Navigation讲解

130The Plow and the Horse in Medieval Europe讲解

TF阅读真题第690篇Egypt in Early World History

TF阅读真题第722篇Easter Island's Statues

TF阅读真题第754篇Frederick Taylor And United States Industry