It is reported that the world’s populatio n was 6 billion in the year 2,000, and it is growing faster and faster. The world’ s population problem is the greatest on e because it brings lots of problems, su ch as water resources problem, more a nd more people losing their jobs and so on. These problems are mainly in the d eveloping countries because the popul ation of the developing countries is ove r 4/ 5 of the world’s popuation. So Chin a, the largest developing country, has k ept the policy “one couple, one child.”