—Do you think ________will be robots in the school in 20 years?

—No,________.

A．there; there won’t

B．they; there will

C．there; they won’t

D．they; there wouldn’t

完整的说明离心力的计算与哪些因素相关？（）

A.离心机品牌

B.台式或落地式

C.塔式或水平转头

D.离心机使用电压

E.旋转半径和每分钟转数