To say what is the right thing to do ("should" is the more common word)
"In her condition, she ought to quit smoking.“
"I believe you ought to apologize.“
"He was watching TV when he ought to have been studying."
aim.uz
How and when do we use modal verbs?
Uses of "shall" (short form: 'll, negative: shall not, shan't)
Used with "I" and "we" to talk about the future (especially in formal British English) "I shall leave tomorrow morning." "I'll never forget you." "We shall overcome." "I shan't be late again.“
2. Used with "I" and "we" to ask questions or make suggestions "Shall I close the door?" "What shall we do tonight?" "Let's start, shall we?"
aim.uz
How and when do we use modal verbs?
Uses of "will" (short form: 'll, negative: will not, won't)
To talk about future actions or future states (not plans) "I hope he will pass his exams." "She'll be very happy to hear this." "They will not be here on time." "You won't feel a thing.“
2. For promises or intentions "Leave it, I will do the dishes." "It must be Joe at the door, so I'll get it." "I won't do that again, I promise."
aim.uz
How and when do we use modal verbs?
Uses of "should" (negative: should not, shouldn't)
To say what is the right thing to do "You should be helping your mother." "If he doesn't like the job, he should tell it to his boss." "If you knew you were going to be so late, you should have called.“
2. To give advice or ask for advice "You should try the new restaurant down the street." "What should I do? Should I tell him the truth?"
3. To show that something is expected or likely to be true
"Let's return home, dinner should be ready by now." "We should arrive there by twelve o'clock." "I should get an e-mail from him soon."