【单选题】A ) Their genetic makeup began to change . B ) Their communities began to grow steadily . C ) Their children began to mix with each other . D ) Their pace of evolution began to quicken .
【单选题】In 1917, Russia was in chaos. The economy was collapsing, there were food shortages and the country was suffering heavy losses in the World War I. Inevitably, people began to lose faith in their ruler...