每个数学问题都有一个解决方案；只是需要时间和努力去找到它。
Every mathematical problem has a solution; it just takes time and effort to find it.
One who never turned his back but marched breast forward, never doubted clouds would break.
Every book is a journey, and every journey is a book.
I don't want to be a teacher. I want to be a friend.
The art of progress is to preserve order amid change and to preserve change amid order.
世界充满了魔法，你只需要相信它。