Piezoelectriccrystals produce an electric current when bent and have many USES - the igniter on a gas barbecue grill being one of them.
压电晶体在发生弯曲时能够产生电流，并且已有很多用途——燃气烧烤的点火器就是其中之一。
2
The most widespread of these known techniques is ultra sonic agitation with piezoelectriccrystals, converting electrical energy into mechanical energy.
最广泛的技术是超声晶体震荡，将电能转化成为机械能量。
3
Explain the characteristics of piezoelectriccrystals and the factors relating to the resonant frequencies of a piezoelectric crystal, and the procedure of the pulse-echo method.