42 Ought to: Modal Auxiliary Verb


A modal verb is a type of auxiliary (helping) verb that has no meaning on its own but it modifies the main verb, changes its meaning and gives more details about the action.

Ought to is a type of auxiliary modal verb used to express obligation and duty through advice or recommendations.


Ought to always has the same form even for the third person singular, and we find this structure in its three forms.


Its structure, in the affirmative form, is:
Subject + ought to + verb + …

Subject ought to Verb
I/You ought to work
He/She/It ought to work
We/You/They ought to work


Its structure, in the negative form, is:
Subject + ought + not + to + verb + …

  • Short version of the negative form is: oughtn’t.
Subject ought to + not Verb
I/You ought not to work
He/She/It ought not to work
We/You/They ought not to work


Its structure, in the interrogative form, is:
Ought + subject + to + verb + …?

Ought Subject to Verb Question
Ought I/you to work ?
Ought he/she/it to work ?
Ought we/you/they to work ?


  1. Weaker obligation/duty
    • You ought to apologise.
    • Smoking oughtn’t to be allowed at school.
    • You ought to get the diploma soon.
  2. Advice
    • You ought to work out more.
    • He oughtn’t to memorise the rule, it’s better to understand it.
    • Ought we to read the syllabus of the course?


Ought to can be considered not to be as strong as must. We use ought to when:

  1. We indicate weaker obligation or duty;
  2. We give and ask for advice (recommendation).


The modal verb ought to expresses obligation or advice. It can be considered to not be as strong as must.

The structures are:

  • Affirmative: Subject + ought to + verb + …
  • Negative: Subject + ought + not + to + verb + …
  • Interrogative: Ought + subject + to + verb + …?

For example:
— Affirmative: “You ought to do your homework to understand the subject.” = Ought to is used to give a recommendation.
— Negative: “You oughtn´t to do your homework to understand the subject.” = Oughtn’t is used to give a recommendation.
— Interrogative: “Ought you to do your homework to understand the subject?” = Ought? is used to ask for a confirmation of a recommendation.
♦ “You must do your homework or you will fail the class.” = Must expresses a stronger obligation.

Let’s revise this content within the {Form} section. Take a look at the {Example} section that shows its use within a context.

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