食物蛋白质的生物学价值主要取决于

A．蛋白质的必需氨基酸比值
B．蛋白质的必需氨基酸和非必需氨基酸比值
C．蛋白质的必需氨基酸含量和比值
D．蛋白质的必需氨基酸总量
E．储留氮与摄入氮比值

Certainly man must () the future, and find ways of providing for his use.

A. look to

B. look up

C. look for

D. look on