How to see version history.
Open a document, spreadsheet, presentation, or drawing.
Click the File menu and select See revision history.
Click a time stamp in the panel on the right to see a previous version of the file.
Examples
「殺処分」
https://docs.google.com/document/d/1YEy1VAA8hLkd7e5IL0e9pqVKEmyX8Gn5Gwjj534Y8t4/edit?usp=sharing
“Animal Euthanasia”
https://docs.google.com/document/d/1m_M1sqMLSsd3qb0ybKYqx2VnrsXXW5aiN0jNkoUdTfA/edit?usp=sharing
To name a file version,
select File
Version history
Name current version.
Examples
Brain Storm
First draft
Final version