---- Was it by cutting down staff  _    _she saved the firm?

---- No, it was by improving work efficiency.

A．when

B．what

C．how

D．that

在单因子试验的方差分析表中列出了S_A、S_e、f_A、f_e

F_A的计算公式是（）。

A.A

B.B

C.C

D.D