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有称中心，这使它们成为压电性候者。

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.

已经有火车站使用乘客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。