You should remind him the submission deadline of the project because he is an absent-minded man.
You must remind him the submission deadline of subject because he is an absent-minded man. He might be late if you do not remind him.
You should remind him the submission deadline of the project because he is an absent-minded man.
You must remind him the submission deadline of subject because he is an absent-minded man. He might be late if you do not remind him.