题目

Tangchang, a town in Chengdu, is well-known for cloth shoes. With over 20 types, Tangchang cloth shoes are strong, comfortable, breathable and friendly to the environment. In 2018, they were added to Sichuan’s intangible cultural heritage list（非物质文化遗产名录） . 63-year-old Lai Shufang has spent over 40 years making Tangchang cloth shoes. Now she is a master. She said there are 32 steps to make a pair, but the most important step is making the soles. Layers（层） of white cloth are glued together with flour paste （糨糊） . “To make good paste, we make it at a tempe化学反应：3Cu+8HNO3（稀）═3Cu（NO3）2+2X+4H2O中，X的化学式为A.CuOB.NO2C.N2OD.NO