043Economic Decline in Europe During the Fourteenth Century讲解

044Effects of the Commercial Revolution讲解

045Eli Terry’s Clock讲解

046England’s Economy in the Sixteenth Century讲解

047Environmental Impact of the Anasazi讲解

048Europe in the High Middle Ages讲解

049European Context of the Scientific Revolution讲解

050Extinctions at the End of the Cretaceous讲解

051Farming New England in Colonial Times 讲解

052Features of Tropical Mammals讲解