There are generally only two places for undergraduate graduation thesis after duplicate checking, one is the database of our school, and the other is the database of HowNet. Students can visit in our school, but the database of HowNet can't, which is related to the internal database of HowNet. HowNet includes plmc detection system, which is specially used to detect undergraduate thesis. The database is a "joint comparison database of college students' papers", that is, all papers detected by plmc detection system will be included. However, because there is no cooperation agreement with the relevant authors, it will not be publicly displayed, but will only be compared during testing.