We know,the population problem has been the world's largest problem.By the year 2000,the world population reached 6 billion,over-population will bring us many problems,for example can cause traffic congestion,employment difficulty,and so on.At present,the development of China's family KouZhan four 5 of all over the world.We China's family planning policy,it is effective control the number of population,reduced the burden.
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