The first is that the paper completely or basically plagiarizes other people's papers, but the plagiarized papers are simply modified and deleted, but there are still many similar fragments and words.
In the second case, although the similarity of the paper is not very high and the contents of the paper are not exactly the same, the similar fragments in the extracted part still exceed the maximum threshold, so the repetition rate of this part will be calculated until the overall repetition rate of the paper is higher than the requirements of the school. This situation is slightly less serious than the first one, and the workload of late detection and duplicate checking is still relatively large, and there are many parts that need to be reduced.
In the third case, the citation symbols are not marked according to the requirements of the paper duplicate checking system, or the duplicate checking system cannot correctly identify this part, but will directly mark these citation parts in red. On the other hand, even if the citation symbol is made, if the length and number of citations exceed the threshold of the paper detection system, it will be judged as repeated red.