单词	mining excavation
释义	mining excavation 采空区
随便看	zero crossing ratio zero-crossing representation zero crossings zero-crossings zero-crossing switching zero-crossing time zero-crossing time intervals zero crossing time pick-off zero-crossing trigger zerocrosslevel zero cross level zero-cross-level zero-cross-level detector zero crossover zero-cross-over trigger zero-cross-over triggering zero cross point zero cross pulse zero cross rate zero-cross ratio zero cross ratio average in short time zero cross signal zero-cross swich circuit zero-cross switch zero cross switch circuit