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

但是一些晶体材料不具有对称中心，这使为压电性的候者。

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.

已经有站使用乘客的脚步为检票口和显示屏供电，还有一个舞蹈俱乐部使用压电技术为灯供电。