[填空题]The promise of finding long-term technological solutions to the problem of world food shortages seems difficult to fulfill. Many innovations(改革，创新) that were once heavily supported have since fallen by the wayside. The proposals themselves were technically (47) , but they proved to be economically unavailable and culturally unacceptable to their consumers.
One characteristic common to unsuccessful food innovations has been that, even with (48) support, they often have not been technologically (49) or culturally acceptable to the people for whom they had been developed. A successful new technology, therefore, must fit the entire socialcultural system in which it is to find a place.
The (50) of new food technologies depends on more than these technical and cultural (51) , economic factors and governmental policies also strongly influence the (52) success of any innovation. Economists in the Anglo-American tradi

[单项选择] The promise of finding long-term technological solutions to the problem of world food shortages seems difficult to fulfill. Many innovations that were once heavily supported and publicized, such as fish-protein concentrates, have since fallen by the wayside. The proposals themselves were technically feasible, but they proved to be economically unfeasible and yielded food products culturally unacceptable to their consumers. Recent innovations such as opaque-2-maize, Antarctic krill (磷虾群), seem more promising, but it is still too early to predict their ultimate fate. One characteristic common to unsuccessful food innovations has been that, even with extensive government support, they often have not been technologically adapted or culturally acceptable to the people for whom they had been developed. A successful new technology, there fore, must fit the entire socio-cultural system in which it is to find a place. Security of crop yield, practicality of storage and costs are much mor
A. basically gloomy but still uncertain
B. somewhat promising but very tentative
C. generally bright and virtually assured
D. endangered by certain technical problems