1, there is a Trojan horse program in the personal computer, which leads to data leakage.

2. The U disk alive notebook has been used by others, and the data has been copied.

3. Computers in schools are basically used by * * *, which means that people with passwords will forward data.

You'd better compare each version carefully, find out the closest date, and then check the computer log file, there will be some traces.

The school computer can also find the school network administrator to compare the records, and how many can find some basis.