The battle of life is already half won by the young man who is brought personally in contact with high officials; and the great aim of every boy should be to do something beyond the sphere of his duties--something which attracts the attention of those who over him.

当一个人开始长得像他的父亲时，他就知道自己正在变老。

忠言逆耳利于行。就像疼痛提醒你哪里病变一样。

关系模型基于谓词逻辑和集合论。