Opening a Tavern Will Make the Tang Dynasty Prosperous Forever?

[No system + Prince Xian Ma + Yan Yu + daily writing + family crusher + multiple female protagonists + popular science in paragraph commentary] Duan Nanhun was the shopkeeper of a tavern in Chang'an City. As long as the tavern was open, there were always many people who liked to ask questions. "Duan Xiaolangjun, what should we do if our Majesty is short of money?" Duan Nan: "Just copy the family." Li Shimin:... "Mr. Duan, what should I do if my brother covets the position of my legitimate son?" Duan Nan: Take your brother's head and ask your father if he will inherit the family business to you. Li Chengqian:...... "Boy Duan, what should I do if the Turks bully me too much?" Duan Nan: Li Ting sweeps the hole and eliminates it physically. Li Jing:...... "Mr. Duan, what should I do if I have chest pain?" Duan Nan: Oops, you have touched upon my blind spot of knowledge, but I happen to be good at treating this, so please come over a little bit. "But Mr. Duan, why are you acting so impatient?" Duan Nan: Nonsense, I'm obviously afraid that you won't be able to hold on. Princess Xiangcheng:......