In the late 1970s, several research groups were trying to determine the cause of the boundary between the geological layers corresponding to the Cretaceous and Tertiary periods, ab...

TF阅读真题第678篇Telescopes

TF阅读真题第691篇Natufians and the Domestication of Grain

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...

  When studying an archaeological site, archaeologists must first try to understand how the society that lived there was organized. Some societies are centrally organized, and...

TF阅读真题第679篇Animals and Forests

TF阅读真题第694篇Formation of Earth's Atmosphere and Oceans

题目: Calcium and Eggshells   Creating an egg requires various nutrients, among which the calcium for the shell is the most difficult to obtain. This is partly because most bi...

TF阅读真题第737篇Chinampas

TF阅读真题第705篇Freehold Society in Colonial New England