The concept of legal validity is crucial for understanding the nature of law.

粮食安全的未来就在波涛之下。

如果你不前进，你就在落后。

"Literature is the mirror that reflects the soul of society, showing us both its beauty and its flaws."

The mistral may howl, but the olive tree bends without breaking.

父母死气沉沉的生活对周围人特别是自己孩子的影响，是无与伦比的。

数学中的合作是必不可少的；没有人能独自解决所有问题。