Let us consider what science and technology have to contribute to the food problem. The si

Let us consider what science and technology have to contribute to the food problem.

The simplest way to increase food production, one might suppose, is to bring more land 【C1】______ cultivation and put more people to work on it. Some of the underdeveloped countries have resorted to this 【C2】______ approach, without notable success. It contains several fallacies. For one thing, it usually means 【C3】______ into marginal lands where the soil and climatic conditions give a poor 【C4】______ . Cultivation may quickly deplete this soil,【C5】______ it for pasture or forest growth. It is often possible, of course, to turn such lands into useful farms by agricultural 【C6】______ ; for instance, a sophisticated knowledge of how to use the available water【C7】______ an irrigation system may reclaim semi-arid grasslands for crop-growing. But the cultivation of marginal lands i6 in any case unsuccessful【C8】______ it is carried out by farmers with a centuries - old tradition of experience or by modern ex pelts with a detailed knowledge of the【C9】______ conditions and the varieties of crops that are suitable for those conditions. Such knowledge is【C10】______ absent in the underdeveloped countries.

【C11】______ , we know that highly developed countries have not increased the【C12】______ of acres under cultivation, 【C13】______ on the contrary have 【C14】______ their marginal lands and steadily reduced the proportion of the population engaged in farming. Efficient farming【C15】______ concentration on the most efficient lands, and it results in greater production with【C16】______ people. The problem of the underdeveloped countries, then is to increase the【C17】______ of their farms and farmers. This would allow them to industrialize and to feed their people more adequately. It is not easy to【C18】______ , how ever. The farmers are conservative and resistant to change【C19】______ their methods of cultivation. The underdeveloped countries are greatly in need of studies and experiments to help them to【C20】______ modern agricultural methods to their own conditions.

【C1】

A．under

B．of

C．by

D．in