Zinc oxide can be reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent. Explain why?

$Al$ is a very reactive metal whereas $Zn$ is comparatively less reactive. $Zn$ being less reactive, its oxide is less stable hence it can be easily reduced by carbon monoxide whereas $Al$ being highly reactive its oxide is stable and cannot be reduced by reducing agent. It can only be reduced by electrolytic redution.