016Art and Culture of Pacific Northwest Communities讲解

048Europe in the High Middle Ages讲解

080Milankovitch Cycles and Glaciation讲解

112The Collapse of the Maya讲解

144Water Supply in Venice讲解

官方评分规则 谈到分数评估，首先是需要明确PET考试评分规则。1、总分评分简单分析下B1 Preliminary（PET）的评分。PET的最终分数是阅读、写作、听力、口语四项的平均分（这点很类似雅思）。最...

Ocean and Atmosphere on Early Earth Where did Earth's ocean water come from? Scientists agree that a large amount of water must have arrived during planet, accretion, which is the ...

第61篇The Origins of Agriculture

第93篇The Agricultural Revolution

第125篇The Extinction of the Dinosaurs