人口增长、 人口质量、 小学生肥胖、 养老与老龄化、 性别比例
1、population aging; outdated and abandoned; to improve the living condition of the aging population ; to respect and appreciate the aged; to provide safety and happiness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.