人口增長、 人口質量、 小學生肥胖、 養老與老齡化、 性別比例
1、population aging; outdated and abandoned; to improve the living condition of the aging population ; to respect and appreciate the aged; to provide safety and happiness
2、the number of males outweighs that of females;the population growth is almost out of control, the humans to live is increasingly circumscribed.
