关系模型基于谓词逻辑和集合论,为数据库管理提供了坚实的数学基础。
History is not just a record of events; it is the soul of a people, their dreams and struggles.
男人会变老,但永远不学好。
对死亡的恐惧源于对生活的恐惧。活得充实的人随时准备死亡。
We must remember that literature is not just entertainment, it has a deeper meaning.