Flickering light increased the duration of the afterimage.Central fixation was stimulated by projecting the afterimage on detailed near work such as reading or sewing. 闪烁光背景增加后像持续时间，利用后像对准阅读材料或精细作业，激发中心凹注视能力，改善注视功能，提高中心凹视力。
A policeman flagged down the car with his flash light. 警察挥动闪光灯让那辆车停下。
He switched on the flashing light and set off the siren. 他交换了在闪光灯和引起了警报器。
