Wanzi (graduated from the Department of Clinical Medicine, although he ended up working in finance, well, it seems that time travel still requires this skill.) And Tuanzi (graduated from the physics department of a university, and finally went to work on software, which has nothing to do with the skills required for time travel.) Are a pair of good friends. One day, they traveled to the Qing Dynasty and became Yinzhen and Yiner. They got together to build a glass vessel to cultivate some penicillin, and by the way, the story of Kang Si, a pair of good friends.
Main character Kang Si, others may appear as the plot develops.
Well, history is amazing, and it may have changed, so I guess there is no pressure to do research.