Future tense or emphatic intention: (1st person) I shall/will return soon.
Strong assertion, command or duty: (2nd/3rd person) You/They shall go to the party.
Questions, polite enquiry: Shall we go to lunch? Shall you drive me home?
Reported speech: I said I should be home soon.
Obligation or likelihood: You should come home now.
Tentative suggestion: I should like to add that . . . .
Conditional: If you should see him, please tell him to call me.