39 Have to: Modals of Obligation

Introduction

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 actions.

Have to is a type of auxiliary modal verb used to express certainty, necessity or strong obligation which comes from outside, from external factors.

Form

Have to can be expressed in the three forms:

Affirmative

Its structure, in the affirmative form, is:
Subject + have/has to + verb + …

  • Have/has: in the affirmative form, the third person singular changes from have to has.
Subject have/has to Verb
I/You have to work
He/She/It has to work
We/You/They have to work

Negative

Its structure, in the negative form, is:
Subject + do/does + not + have to + verb + …

  • Do/does: in the negative form, the third person singular changes from do to does;
  • Short forms of the negative form are the same as the short form of present simple: I don’t – you don’t – he doesn’t…
Subject do/does + not have to Verb
I/You do not have to work
He/She/It does not have to work
We/You/They do not have to work

Interrogative

Its structure, in the interrogative form, is:
Do/Does + subject + have to + verb + …?

  • Do/does: in the interrogative form the third person singular changes from do to does.
Do/Does Subject have to Verb Question
Mark
Do I/you have to work ?
Does he/she/it have to work ?
Do we/you/they have to work ?

Example

  1. Certainty/reasonably expected
    • This has to be her flat! She said it’s floor 2, flat 13.
    • This house doesn’t have to be in a good state.
    • Do they have to be rich? They live in a luxury flat in the city center.
  2. Strong obligation
    • The owner said I have to move to another house.
    • She doesn’t have to clean the kid’s clothes everyday.
    • Do we have to clean the mess we made in the kitchen?
  3. Necessity
    • have to buy a new fridge, the one I have is broken.
    • Alissa doesn’t have to search for a student flat.
    • Do they have to paint the walls?
  4. No obligation (negative)
    • We don’t have to ride a horse.
    • He doesn’t have to clean his room.
    • They don’t have to return from the island

Use

Have to is used to show that there is an obligation imposed by external factors. It is used to show:

  1. That something is reasonably expected or is a certainty (affirmative, negative, interrogative);
  2. A strong obligation (affirmative, interrogative);
  3. A necessity (affirmative, negative, interrogative);
  4. No necessity or no obligation to do something (negative).

Summary

The modal verb have to expresses certainty,  strong obligation, necessity or no obligation which comes from outside, from external factors.

The structures are:

  • Affirmative: Subject + have/has to + verb + …
  • Negative: Subject + do/does + not + have to + verb + …
  • Interrogative: Do/Does + subject + have to + verb + …?

For example:
— Affirmative: “I have to go to school every day.” = The subject is obliged to go to school every day.
— Negative: “She doesn’t have to go to school every day.” = It is not necessary for the subject to go to school every day.
— Interrogative: “Does she have to go to school every day?” = We ask if the subject is obliged to go to school every day.

NOTE: Don’t have to (negative form of have to) usually expresses that something is not necessary to be done.

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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