.

--- Shall we go shopping together this afternoon?

--- _______. I will be very busy then.

A．Out of question

B．Out of the question

C．No problem

D．Good idea

临床检验质量控制方法中确定质量控制方法性能的关键指标是（）

A.标准差

B.靶值

C.控制规则

D.极差

E.质量控制测定值的个数