题目

Japanese students work very hard but many are unhappy, They feel heavy pressures from their parents to do well in school, Most students are always being told by their parents to study harder so that they can have a wonderful life, Though this may be good ideas for those very bright students, it can have very bad results for many students who are not quick enough at learning Unfortunately, a number of students killed themselves, Others are after comfort in using druges, Some do bad things with trouble-makers and turn to crime, Many of them have tried very hard at school but have failed in the e下列群落演替中，属于原生演替（初生演替）的是A．从湖泊到森林的演替B．从火山岩（裸岩）开始的演替C．从荒废农田开始的演替D．从火灾过后的草原开始的演替