Rule of 7 in research. You can find out anything if you are willing to go seven levels. If the first source you ask doesn’t know, ask them who you should ask next, and so on down the line. If you are willing to go to the 7th source, you’ll almost always get your answer.
数学不是关于数字、方程、计算或算法的:它是关于理解的。
Education is an ornament in prosperity and a refuge in adversity.