— Mum, will you buy me the new iPad after the Entrance Examination?

— I’m afraid I ________, dear. We are short of money now.

A．mustn’t

B．can’t

C．shouldn’t

D．needn’t

当键槽铣刀的轴线对准工件中心后，键槽铣刀圆柱度差，是造成键槽对称度超差的主要原因。