结构性流动指由于社会结构的变化而引起的大规模的社会流动,其特点是个人原因而发生的社会流动。()

A legal classification system for video games.
B. A barrier mechanism in video games.
C. Putting computers in public areas at home.
D. Less supervision on children"s use of Internet.

A. is the first choice for communication and entertainment
B. will cause socioeconomic disaster in the future
C. hasn"t made prominent progress in the past few years
D. is in great need of rules to be established and enforced