population is a great c_ in developing country than in developed county

population is a great c_ in developing country than in developed county
population is a great c_ in developing country than in developed county

population is a great c_ in developing country than in developed county
challenge 挑战
与发达国家相比,在发展中国家的人口问题更是一个巨大的挑战.
请记得采纳的呵!