Around the world, governments have subsidized the housing of middle and upper-income groups.全世界各国政府都为中高收入群体提供过住房补贴。In effect, growth is contingent upon improved incomes for the mass of the low-income population.事实上，增长依靠的是广大低收入群体收入的增加。Elderly people often belong to a low income group.老年人往往属于低收入群体。