每个数学问题都有解决方案，但并非每个解决方案都显而易见。
Every mathematical problem has a solution, but not every solution is immediately apparent.
The only thing necessary for the triumph of evil is for good men to do nothing.
水和空气，所有生命赖以生存的两种基本流体，已经变成了全球的垃圾箱。