【简答题】It’s just a small, white envelope stuck among the branches of our Christmas tree. No name, no address. It has peeked through the branches of our tree for the past 10 years. It all began because my hus...
【简答题】Why did humans evolve to walk upright? Perhaps because it’s just plain easier. Make that “energetically less costly”, scientifically speaking. Bipedalism—walking on two feet, is one of the defining ch...