My tutor revised the first draft of my thesis and marked many characters in red. Mainly in terms of format, I changed it according to his request and marked it green.
Yes, your tutor uses modification software, which has been modified on it before and automatically generated, as long as it is different from the tutor's modification. But I suggest that you'd better re-write an electronic document (in fact, just change the part you want to change and paste the other contents intact) and send it to him, so that your face looks clean and your tutor can see it clearly.