GRE Reading Comprehension: ETS-GRE阅读ETS - W1JFE21HX0F840VX7

According to the author, which one of the following is required in order that one be a professional? A. significant prestige and a title B. "know-how" in a particular field C. a long and difficult educational endeavor D. a commitment to political justice E. a public confession of devotion to a way of life