历史的地理枢纽是世界上那些海权无法触及但却是陆权天然堡垒的区域。

"The challenge in theoretical computer science is not just to solve problems, but to understand why they are hard to solve."

说话有分寸则少得罪人；行为有节制则少悔恨；爱慕有节制则要求少；快乐有节制则祸败少；饮食有节制则疾病少。