She excitedly suggested a new plan, but the manager shot it down right away.

shot it down 是一个动词短语，由 shoot（射击）和 down（向下）组成。字面意思是"击落"，引申为"拒绝、否决"某个提议或想法。这个短语形象地比喻像击落飞机一样快速否定一个提议。