将一定质量的Na₂O₂与Na的混合物与足量水反应，收集到0.03 mol的气体混合物。此混合气体经点燃，恰好完全反应，则Na₂O₂与Na物质的量之比是(    )

A．1∶1

B．2∶1

C．1∶2

D．3∶2

Tom is expecting a pet for long, but his daddy has no time to buy _________ for him.

A．it

B．one

C．this

D．that