John, look at the time. ____ you play the piano at such a late hour?

A．Must

B．Can

C．May

D．Need

以下转化能通过一步反应实现的是

A．Al₂O₃→Al(OH)₃

B．SiO₂ →H₂SiO₃

C．Fe→FeCl₂

D．Na₂O₂→NaOH