There are already train stations that use passengers' footsteps to power the ticket gates and displays, and a dance club where piezoelectricity helps power the lights.

如今， 已有火车站利用乘客的脚步为闸机屏电，还有一家舞借助压电效应为灯能量。

But some crystalline materials don't possess a center of symmetry, making them candidates for piezoelectricity.

然而， 某些晶体材料缺乏对称中心，这使得它们成为压电效应的候选材料。