单选题 Man cannot continue (26) his numbers (27) the present rate. In the (28) thirty years man will face a period of crisis. (29) experts believe that there will be a widespread food (30) Other experts think this is (31) pessimistic, and that man can keep things (32) worse than they are now. But (33) that two thirds of the people in the world are undernourished or starving now. One thing that man can do is to limit (34) of babies born. The need (35) this is obvious, but it is not easy to achieve. People have to (36) to limit their families. In the countries of the population (37) ,many people like big families. The parents think that this (38) a bigger income for the family and ensures there will be someone in the family who will look (39) them in old age. Several governments have (40) birth control policies in recent years. (41) them are Japan, China, India and Egypt. In some (42) the results have not been (43) . Japan has been an exception. The Japanese adopted a birth control policy in 1948. People (44) to limit their families. The birth rate fell from 34.3 per thousand per year to about 17.0 per thousand per year (45) .