The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.
实际的强度水平取决于诸如大城市的物理布局、人口密度和生产活动之类的因素。
2
During this critical phase, there will be too few young, productive people who can produce the prosperity required to care for the country's aging population.
在那个紧要阶段，将会有太少的年轻，有生产力的人可以营造能够负担照顾这个国家老年人口的富足。
3
This age group is the most economically productive part of the population, and if the epidemic continues to spread through that age group, there will be serious economic consequences in the future.