填空题

The advantages and disadvantages of a large population have long been a (11) of discussion among economists. It has been argued that the supply of good land is limited. To feed a large population, inferior land must be (12) and the good land worked intensively. Thus, each person produces less and this means a lower income than could be (13) with a smaller population. Other economists have argued that a large population gives more (14) for specialization and the development of (15) such as ports, roads and railways, which are not likely to be built unless there is a big demand to (16) them. One of the difficulties in carrying out a world-wide birth control program lies in the fact that official attitudes to population growth (17) from country to country depending on the level of industrial development and availability of food, space and natural resources, (18) whatever the consequences may be. In a highly industrialized society the problem may be more complex. (19) .When the pressure of population on housing declines, prices also decline and the building industry is weakened. (20) , rather than one which is stable or in decline.