Difficult circumstances serve as a textbook of life for people.
In mathematics, you don't understand things. You just get used to them.
大自然是伟大的老师,当别人睡觉时,我从她那里学得最好。
当你找不到人来喝你沏的茶时,当没有人需要你时,我想这就是人生完结的时候。