One month's time, because students will be asked to hand in their homework at the end of the term, and when students hand in the electronic version of their homework, it will be about one month before the end of the term.

The retention of the electronic version of the big homework is to grade the students' final grades, and when the grades are finished, it is naturally for the students. Homework should be deleted, because these documents are basically useless after the scores are recorded, which means that students' homework will basically be deleted after the scores are recorded.

Save it for one month and it will be deleted, otherwise it will take up a lot of memory. The teacher's words were basically deleted within a month.

Students' words will be deleted immediately after handing in their homework, because although the memory occupied by the document is not large, it will naturally slow down the speed of the computer or the speed of the mobile phone if it accumulates too much, so students usually delete the copy in the mobile phone or computer immediately after handing in their homework.