The results show that when molecular mass of PET prepolymer with 2 functional groups increases, impact strength of JMZ gun propellant descends.是什么意思_The results show that when molecular mass of PET prepolymer with 2 functional groups increases, impact strength of JMZ gun propellant descends.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句