Modals of Obligation - Have to

Verbs

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

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

Affirmative

The Affirmative form of the verb Have to has this structure:
Subject + “Have/has to” + verb.

Have/Has: In Affirmative form the third person singular changes from “have” to “has“.

SUBJECT	HAVE TO	VERB
I/You	have to	work
He/She/It	has to	work
We/You/They	have to	work

Negative

The Negative form of the verb Have to has this structure:
Subject + “do/does” + not + have to + verb.

Do/Does: In Negative form the third person singular changes from “Do” to “Does“.

PERSON	NEGATION	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

The Interrogative form of the verb Have to has this structure:
“Do/Does” + subject + have to + verb + …?

Do/Does: In Interrogative form the third person singular changes from “Do” to “Does“.

DO	PERSON	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	…?

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 for this house? They live in a 3 bedroom luxury flat in the city center.
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?
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 obligation (Negative)
- I have to tell you where to look for accommodation.
- He doesn’t have to clean his room.
- Do they have to share a flat?

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

That something is reasonably expected or is a certainty (Affirmative, Negative);
A strong obligation (Affirmative, Interrogative);
A necessity (Affirmative);
Don’t have to (Have to - Negative form) is used to show that there is no obligation or necessity (Negative).

We use the Modal verb “Have to” to express certainty, necessity or strong obligation which comes outside, from external factors. “Have to” can be expressed in the three forms (Affirmative, Negative and Interrogative).

The structure for Have to in its three forms is:

Affirmative: Subject + have to + verb (“has” for the third person);
Negative: Subject + do + not + have to + verb (“does” for the third person);
Interrogative: Do + subject + have to + verb + …? (“does” for the third person).

For example:
— “I have to go to school every day.” = It means that the subject is obliged to go to school every day.
— “She doesn’t have to go to school every day.” = It means that it is not necessary for the subject to go to school every day.
— “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” (Have to - Negative form) in its Negative form usually expresses that something is not necessary to be done.

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