‘Should is a modal verb. Should + Verb (base form of infinitive) ‘
‘Modal verbs are auxiliary verbs (also called helping verbs) like can, will, could, shall, must, would, might, and should. After a modal verb, the root form of a verb is generally used.’
‘All modal verbs are auxiliary verbs, which means they can only be used with a main verb. … The modal verbs are; will, would, shall, should, can, could, may, might and must.’ Eg.
I posted the cheque yesterday so it should arrive this week.
The president insists that the prime minister should attend the meeting
The manager recommended that Mary should join the company.
It was necessary that everyone should arrive on time.
He asked me what time he should come.
He should go. He should work. She should worry.
John should get a haircut.
He should stop drinking.