population mobility

例句：

1. 1. The city's population mobility has significantly increased in recent years.
   近年来，该城市的人口流动性显著增加。
2. 2. The study found that population mobility is a major factor in the spread of diseases.
   研究发现，人口流动性是疾病传播的主要因素。
3. 3. The government has implemented policies to encourage people to move from rural areas to urbancenters, increasing population mobility.
   政府实施政策鼓励人们从农村地区迁往城市中心，增加人口流动性。