If you have no enemies, you're dead.

农业的故事是人类生存与智慧的故事。

The mother-child relationship is paradoxical and, in a sense, tragic. It requires the most intense love on the mother's side, yet this very love must help the child grow away from the mother, and to become fully independent.

最优财政政策要求税率随时间平稳变化，仅对政府支出的永久性变化作出反应。