GRE Text Completion: JiJing 1373-GRE填空机经1373题 - GX7784Q3WHY197L3A

When studying human history, one must be aware that the ____________ between historical periods are arbitrary; certainly none of the people alive at the time were aware of a shift from one era to another. A. judgements B. ideologies C. innovations D. demarcations E. episodes