安装抽油机时，冲程长度2～3m时，曲柄剪刀差小于（）。
A、2mm
B、3mm
C、4mm
D、5mm
参考答案：B
已知：某泵Q=70m3/h，H=65.84m，铭牌功率为18.2KW，求①有效功率Ne，②效率η。
According to the crowding-out effect, which of the following statements is FALSE The sale of government bonds used to finance excess government spending will:（）
A. raise the real interest rate.
B. raise the nominal interest rate.
C. increase the profitability of corporate investment projects.
