1. Modals

2. Modals are auxiliary verbs that are used with main verbs to give advice and express ideas like ability, necessity, or possibility. Some examples of modals are can, might, and should. Most modals have more than one meaning. For example, can expresses possibility, ability, and permission.
Phrasal modals are expressions with meanings similar to those of modal auxiliaries. They include expressions like be able to, be supposed to, and have to.

3. Forming Affirmative Statements with Modals in the Present Tense (modal + base V)
You
He / She / It + We
They
can
could
will
would
should + eat.
ought to
may
might
must
had better

4. Forming Negative Statements with Modals in the Present Tense (modal + not + base V)
You
He / She / It + We
They
cannot
could not
will not (won’t)
would not
should not + eat.
ought not to
may not
might not
must not
had better not

5. Remember!
He may need extra time to finish his paper.
She should study more.
NOT
He may needs extra time to finish his paper.
She should studies more.

6. Phrasal modals with be and have change form to agree with their subjects.
I am supposed to practice today.
Michael has to help his parents move.
John and Kim are able to do the homework.

7. Forming Modals in the Past Tense
Present
can
have to / has to
am / is / are able to
am / is / are supposed to
Past
could
had to
was / were able to
was / were supposed to

8. I can play the violin now, but when I was a child, I could play the piano.
We had to call the police last night to report the crime.
The plane wasn’t able to take off because of the snow this morning.
We were supposed to study for the test last night, but we went to the movies instead.

9. Practice: Correct the errors in modal forms.
Financial aid can helps many students.
Desert neighborhoods has to save water.
You should study not with the TV on.
Robert have to prepare for his speech.

10. Forming Affirmative Statements with Modals in the Past Tense (modal + have + -en/-ed)
You
He / She / It + We
They
could have
would have
should have
ought to have + eaten.
may have
might have
must have
had better have

11. Forming Negative Statements with Modals in the Past Tense (modal + not + have + -en/-ed)
You
He / She / It + We
They
could not have
would not have
should not have
ought not to have
may not have + eaten.
might not have
must not have
had better not have

12. I should have stayed home last night.
He must have studied a lot to get such a good grade.
She may not have gotten an A on the test.
We should not have skipped class on Monday.

13. Practice: Correct the errors in modal forms.
William should of traveled with us last summer.
Andrea should be wait at the airport when you arrive.
Josh should have not written that letter to this girlfriend.
Robin could played the piano when she was younger.
Norman had not to work yesterday.

14. Showing Ability Present and Future can be able to will be able to
I can lift 50 pounds.
She is able to run a marathon.
He will be able to come.
Past
could
was/were able to
Last year I could lift 100 pounds.
She wasn’t able to come.

15. Making Requests Present and Future can could would Can you help me?
Could you bring dessert tomorrow night?

16. Showing Possibility Present and Future can may might could
He might change his major.
We may leave tomorrow.
Past
may have
might have
could have
I could have left early, but I didn’t.

17. Showing Near Certainty
Present and Future
must
John looks awful. He must be sick.
Past
must have
The ground is all wet. It must have rained.

18. Asking for and Giving Permission
Present and Future
can
could
may
May I ask you a question?
You may use my car on Sunday.

19. Showing Necessity Present and Future must have to
Do you have to work right now?
Must you work tomorrow?
Past
had to
She had to take the medicine.

20. Showing Prohibition Present and Future cannot must not
Cars cannot turn right at this intersection.
You must not take so many units next semester.

21. Showing Lack of Necessity
Present and Future
do not have to
will not have to
I do not have to take the exam.
We will not have to go next time.
Past
did not have to
They did not have to answer the question.

22. Giving Advice/Making Suggestions
Present and Future
had better (not)
should
ought to
could
can
You can borrow that book from the library.
We had better leave early tomorrow.
Past
had better (not) have
should have
ought to have
could have
You ought to have called your mother on her birthday.

23. Showing Expectation Present and Future be supposed to will be able to
I am supposed to be in class right now.
They are supposed to study tonight.
Past
was/were supposed to
We were supposed to stay home last Friday night.

24. Showing Preference Present and Future would rather
John would rather write an essay that take an exam.
They would rather start school next fall than spring.
Past
would rather have
I would rather have eaten dessert first.

25. Repeated Past Action Past would
When he was younger, he would read the same book over and over again.

26. Practice: Correct the errors in modal use.
Since Carla’s surgery, she doesn’t have to eat fatty food.
Mohammad wasn’t here last night, but he may have been because we had a good time.
May you call me at home tonight?
We’re not sure where they went last night, but they would have been at the movies.
There is one research paper due. I must have completed it to pass the class.