Modals of necessity such as must, have to, and have got to express that something is obligatory or required rather than optional. Must is the strongest and most common in writing, while have got to is more informal in speech. Have to can be used in all tenses and for questions to indicate necessity. These modals are followed by the base form of a verb to show that an action is necessary or prohibited in the present or future.

1. Modals of necessity
Barbora Richtarcikova

2. Modals
• Modal verbs are helping/auxiliary verbs that express ideas
like ability, permission, possibility, and necessity. Many
modal verbs have more than one meaning. They are always
followed by the simple form of a verb.
Example:
• John has to go home.
 This shows that John has a necessity or obligation to go home.

3. Modals of Necessity
• The modal verbs must, have to and have got to show that
something is not optional; it is necessary.
• Must is the strongest modal verb of the three and is most
common in writing. It is unusual to use must in questions.
• Have got to is most common in informal speech. It is not
used in questions.
• Have to is the most commonly used modal of obligation. It
is useful for forming questions and negatives.

4. Must
• Use must to tell when something is necessary for present and
future tenses.
Examples: I must study hard.
I must study next week.
• Use must not when something is prohibited (when there is no
choice).
Example:
We must not smoke here.
• In spoken English, can’t is often used instead of must not.
We can’t smoke here.

5. Have got to
• Use have got to to tell when something is
necessary for present and future tenses.
Example:
I have got to study tonight.
• Have got to is often contracted as: I've got to and
sounds like “I've gotta...”

6. Have to
• Use have to for all tenses
Examples:
We have to start now.
We had to do a lot of homework.
We will have to finish the project next week.
• Use don’t / doesn’t have to when something is not
necessary (when there is a choice)
Example:
We don’t have to go to the party tonight.

7. Have to
• Use have to for questions in all tenses.
Examples:
Do you have to ask your parents first?
Will she have to travel again?
• Be careful! The subject and verb must agree
for he/she/it subjects AND the question form
requires “Do/Does/Did”.
Example:
She has to study tonight.
Does she have to study tonight?

8. Let’s practice!
1. New drivers ____________ take a test in order to get a
driver's license. They have no choice.
2. A: ____________ go to work today? B: No, I don't,
because it's Sunday.
3. I'm sorry, Mom. I ____________ call you back later. My
cell phone battery is dying.
4. A: ____________ John ____________ study very much
yesterday? B: No, he didn't.

9. Answers
1. New drivers must take a test in order to get a driver's
license. They have no choice.
2. A: Do you have to go to work today? B: No, I don't,
because it's Sunday.
3. I'm sorry, Mom. I have got to call you back later. My cell
phone battery is dying.
4. A: Did John have to study very much yesterday? B: No, he
didn't.

10. Thank you!