短语词组短语roof weakening 顶板弱化Weakening Venom 衰弱毒素strain weakening 变弱化Phonetic Weakening 语音弱化Weakening slope 弱化值;和弱化值weakening coefficients 弱化系数And Weakening 战和弱化weakening operator 弱化算子weakening ability 能力减弱 返回 weakening