【单选题】All animals in nature must learn to to a changing environment in order to survive.
【简答题】In order survive, to feed, clothe and shelter himself and his children, man is engaged in a constant struggle with the nature.
【简答题】是国民经济的主导产业, 是中国的第一大能源。
【单选题】These industries are trying to improve their efficiency in order to survive international ______.
【单选题】(1)工业管道的沿程阻力系数,在紊流过渡区随雷诺数的增加:
【简答题】(1)工业管道的沿程阻力系数,在紊流过渡区随雷诺数的增加:)A. (a)增加 B. (b)减少 C. (c)不变