---Everybody is playing on the playground. Can I join them , Miss Lin?

--- __________________   Not until you have completed the Maths exercises.

A．Why not?

B．Will you?

C．I hope so.

D．I’m afraid not.

成本管理的成本分类中不包括（）

A、硬件成本

B、软件成本

C、人员成本

D、机会成本