Every morning when we wake up, we have two choices. We can choose      to be in a good emotion      to be in a bad emotion. Why not choose the positive side of life?

A. neither, nor     B. either, or         C. not only, but also

已知某斗容量1m³正铲挖土机，机械台班产量为476m³，机械利用系数0.85，则它在正常工作条件下，1h纯工作时间内可以挖土约（）m³？。

A.47

B.51

C.56

D.70