39 Have to: Modals of Obligation
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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;
| 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 |
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…
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
A 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?
A necessity
- I 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?
No necessity or obligation to do something (negative)
- We don’t have to sell the pig.
- He doesn’t have to clean his room.
- They don’t have to return from the island.
Strong is reasonably expected or in a certainty
- This has to be her flat! She said it’s floor 2, flat 13.
- The roses don’t have to be in a good state.
- Do they have to boast like that? We know they are rich.
Use
We use have to to show that there is an obligation imposed by external factors.
It refers to:
- A strong obligation (affirmative, interrogative);
- A necessity (affirmative, negative, interrogative);
- No necessity or no obligation to do something (negative);
- Something is reasonably expected or is a certainty (affirmative, negative, interrogative).
Summary
The modal verb have to expresses certainty, strong obligation, necessity or no obligation which comes from outside, from external factors.
We can use it in its different forms:
- Affirmative: We start with the subject followed by have to and the verb. In the third person singular, we use has.
- Negative: We start with the subject followed by do not have to and the verb. In the third person singular, we use does.
- Interrogative: We start with do followed by the subject, have to and the verb (the sentence ends with a question mark). In the third person singular, we use does.
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.
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