“The defense of Beijing”的概念、定义、翻译、参考文献-科学参考

单词	The defense of Beijing
释义	The defense of Beijing Encyclopedia 历史学政治史释 The defense of Beijing北京保卫战中国明代正统十四年（1449）蒙古瓦剌部骑兵在首领也先率领下攻打明朝首都北京，明朝军民在明景帝领导、于谦主持下开展的一场首都保卫战。
随便看	improperly primitive form improper mapping improper maximum improper minimum improper motion improper movement improper multiple integral improper node improper notation improper number improper orthogonal mapping improper orthogonal matrix improper orthogonal transformation improper partial graph improper plane improper point improper principal ordinal improper prior improper quadric improper quotient object improper rational function improper refinement improper representation improper rotation improper rotation group

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