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举一反三
【单选题】A．此食物网共有7条食物链 B．磷虾在不同食物链上都属于同一营养级 C．硅藻既是生产者，又是分解者 D．严禁过度捕杀蓝鲸由于其对该食物网影响最大
A.
下图为南极某海域的食物链，据图判断正确的是（）。
B.
【单选题】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 fi...
A.
basically gloomy but still uncertain
B.
somewhat promising but very tentative
C.
generally bright and virtually assured
D.
endangered by certain technical problems
【单选题】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 fi...
A.
it is a more recent innovation that the use of fish-protein concentrates
B.
it can be stored as easily as other varieties of maize
C.
it is more popular than the fish-protein concentrates
D.
it may be more susceptible to insects than other varieties of maize