过去半个世纪最重要的政治发展是自由民主在世界范围内的传播。
The most important political development of the last half century has been the spread of liberal democracy around the world.
The United States has no permanent enemies, no permanent friends, only permanent interests.
I have always preferred working on concrete problems rather than abstract theories.
一般人的毛病，就是容易受局部的蒙蔽，因而不能明白大道理。眼光不妨放长远一些，站得高一些，能看得更广，格局更大。
The world is full of obvious things which nobody by any chance ever observes.
I don't let anyone define me.
在算法的研究中，我们经常发现最有效的解决方案也是最优雅的。