It is imperative that the
***** NOT A TEACHER *****
Good morning, Ali Sa.
(1) This is called the subjunctive.
(2) When you get time, please type the word in the search box. You may find some helpful threads.
(3) It is important/ necessary/ imperative that Tom
be here on time every day.
bring his books to class every day.
not talk so much in class every day.
(4) As you can see, we do not use the "s" form with the subjunctive.
(5) When I say it is important/ necessary/ mandatory, that is only
my opinion or wish. It is not reality. So we do not use "s."
(a) Here is reality:
(i) Tom is on time every day.
Tom brings his books every day.
Tom talks too much every day.
It is imperative (ONLY my opinion) that a student study (no "s") hard every day.
Have a nice day!