长龙是什么形成的

简介：Although the fine Western iron had not yet been delivered to the capital, time did not wait for me. Zhu Cihong sent people to collect more than ten kilograms from major shops in the capital, and handed it all to Bi Maokang to make the main spring of the fusilla gun. After more than a month of experimentation and tossing, the first sample was finally made.