Modal verbs like may, might, must, have to, and can are used to modify other verbs to express meanings like possibility, obligation, permission, and prohibition. May and might are used to talk about possible future actions and can take negative forms with "not". May is also used to ask for or give permission. Have to expresses obligation, while must refers to duties and rules. Mustn't, can't, and cannot are used to express prohibition. A base verb form follows modal verbs.

2. 
Modal verbs are used to modify
other verbs and to express if an
action is recommended,
possible, obligatory, prohibited,
etc.

3. 
These modal verbs are used to talk about a possibility in the
future.
A: What are your plans for tomorrow?
B: I’m not sure. I might/may visit* my grandparents.
* Base form verb.

4. 
You can use may and might in a
negative form by writing not
after the modal verb.
 Lisa may not / might not go
to the concert. She doesn’t
have tickets yet.
 We may not / might not cook
this weekend.

5. 
An additional use of may is to
give or ask for permission (in a
formal way).
May I sit here?
You may have a cookie when
you finish your lunch.
 You may not watch TV. You
didn’t clean up your room.

6. 
These modal verbs have the same
form for all the pronouns.
Use a base form verb after modal
verbs.
May and might are never contracted.

7. 
We often use have to to say that something is
obligatory.
e.g.
Children have to go to school.

8. 
Affirmative I have to wear a uniform to school .
Susan has to clean her room.
Questions Do you have to work on weekends?
Yes, I do/No , I don’t
Does Jack have to wear a suit at work?
Yes, he does/No, he doesn’t

9. 
We use it to express that there is no obligation or
that something is not necessary.
e.g.
I don't have to work on Sundays.
You don't have to eat anything you don't like.
Mike doesn’t have to take the kids to school.

10. 
We use it to express
obligation or duty. This also
refers to laws and regulations.
e.g.
I must learn all of these rules
about modal verbs.
People must turn off their cell
phones before the movie starts.

11. 
Use a base form verb after must.
Affirmative You must wear a
seatbelt at all times .

12. These modal verbs are
used to express
prohibition.

13. 
I mustn't forget my keys.
You mustn't disturb him.
Students must not be late.
I can’t be late for class.
You can’t use your phone in
class.
Students cannot drink alcohol around
the building.

14. 

15. 