◎ 以子之矛,攻子之盾 yǐ zǐ zhī máo,gōng zǐ zhī dùn[Turn sb's battery against himself;Fight sb.with his own weapon] 用你自己的矛来刺你自己的盾。比喻用对方的论点来驳斥对方 -----------------国语辞典:比喻以对方的观点、理论来反驳对方。语本《韩非子.难一》:「楚人有鬻楯与矛者,誉之曰:『吾楯之坚,物莫能陷也。』又誉其矛曰:『吾矛之利,于物无不陷也。』或曰:『以子之矛,陷子之楯何如?其人弗能应也。』」英语 lit. use sb's spear to attack his shield (idiom, derived from Han Feizi 韓非子|韩非子); turning a weapon against its owner, fig. to attack an opponent using his own devices, hoist with his own petard
◎ 以毒攻毒 yǐdú-gōngdú[Take a bit of the dog that bit you;Evil must be driven out by evil] 原义为用毒药治毒疮,引申为利用坏人、坏事之间的矛盾使其自取灭亡 而劫痼改积,巴菽殂葛犹不得而后之以毒攻毒,有至仁焉。——宋· 罗泌《路史·有巢氏》-----------------国语辞典:用有毒的药物来治疗毒疮等疾病。比喻用狠毒的手段来对付狠毒的手段或人。元.陶宗仪《南村辍耕录.卷二九.骨咄犀》:「骨咄犀,蛇角也,其性至毒,而能解毒,盖以毒攻毒也。」《三侠五义.第一回》:「我何不以毒攻毒,叫陈林掌刑追问?他二人做的事,如今叫一人受苦,焉有不说的道理?」英语 to cure ills with poison (TCM), to fight evil with evil, set a thief to catch a thief, to fight fire with fire德语 Gift durch Gegengift bekämpfen (S)法语 combattre le poison par le poison, combattre le mal par le mal, se servir du poison comme antidote
◎ 以防万一 yǐfáng-wànyī[just in case;be ready for any eventualities be prepared for all contingencies] 预防可能的或预期的突然变故 加强安全检查,以防万一-----------------国语辞典:预先设想、考虑,以防备突发的状况。如:「近来天气多变化,最好带把伞出门,以防万一。」