USE OF MUST
To show the duty / obligation, instruction strong advice, Compulsion and necessity-
- I must do my duty.
- You must help the needy.
- You must obey your Parents.
- Staff must be at their desk 9.00.
- Pass jams must use the over bridge.
- It is raining so I must go in.
- I must finish the work today.
- We must do as we are told.
To show probability or like likelihood, prohibition emphatic advice. Question & answer.
- He must be mad to do that.
- He must be an idiot.
- There must be fifty people there.
- You must not tell a lie.
- You must not drive fast.
- You must not miss the film.
- Must I go with you?
- Yes, you must.
USE OF OUGHT TO
To show moral or social obligation and advice.
- We ought to help the poor.
- You ought to respect your teacher.
- We ought to walk every morning.
- The medicine ought to be taken in time.
- Coffee ought to be taken while it is hot.
To show probability, guess sensible action, order and duty / obligation.
- Rana ought to be here now.
- He ought to have invited him.
- You ought to do it.
- You must do it.