as bright as a button看字面意思可能会理解为“像扣子一样亮”，其实际意思是“聪明极了，非常活泼聪明”。

【例句】
My little daughter is as bright as a button.
我的小女儿非常活泼聪明。

Tom's little son is as bright as a button at such a young age.
Tom的小儿子，小小年纪就非常聪明。