永远不要回头看，除非你想走回去。
Instead of singing like the birds, I silently smiled at my incessant good fortune.
The only purpose for which power can be rightfully exercised over any member of a civilized community， against his will， is to prevent harm to others.
Every mathematical problem has a solution; it just takes time and creativity to find it.
The time is always right to do what is right.