Therefore a PDC bit with new compound cutting structure is developed in the light of the characteristics of gravel formation and soft-hard interbedded formation.是什么意思_Therefore a PDC bit with new compound cutting structure is developed in the light of the characteristics of gravel formation and soft-hard interbedded formation.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句