Every setback is a setup for a comeback.
The past is always there, and it's always different every time you look at it.
学习数学的最好方法就是去做数学。
Making something variable is easy. Controlling duration of constancy is the trick.
没有分析,就没有合成;没有合成,也就没有分析。
Never be afraid to take risks. The biggest rewards often come from the biggest risks.