The X in Sun Ruicao's years refers to Beijing University of Technology, because he graduated from Beijing University of Technology, and the "Four Dyeing Tanks" refers to Beijing University of Technology, Beijing Foreign Studies University, Capital Normal University and Beijing Institute of Civil Engineering and Architecture, because these four schools are now or have been loosely managed, and many things with bad atmosphere and bad influence have happened, especially for men and women. In some versions, Beijing Institute of Fashion Technology is also one, but no matter which version. .