how to use ought to, should and must in Q3

Your query isn't clear to me. Could you please specify the context in which you are asking yoru question? Here is a small explanation of where to use ought to, should and must. Hope this helps:


They are used as past equivalents of shalland will.

Should is used in all persons to express duty or obligation.

  • We should obey traffic rules;

  • You should have kept your word.

Should is used to express a supposition that may not be true.

  • If it should rain, they will not come;

  • If he should see me here, he would be irritated.



Must is used to express necessity or obligation. For instance:

  • You must improve your language;

  • They must wake up early to catch the train.

It could also express logical certainty. For instance:

  • She must have read the book;

  • You must watch the movie.


Ought to expresses moral obligation or desirability. It can also be used to express probability. For instance:

  • We ought to forgive and forget;

  • You ought to be on time for the interview;

  • Prices ought to come down soon;

  • This maid ought to be useful.

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