1. Modal verbs

2. GENERAL POINTS: Structure
They work with the main verb to add extra meaning to a sentence: obligation, permission, possibility …
We put an infinitive without TO after most modal verbs (but not ought to)
you shouldn’t smoke.
he must get up early.
*But: Students ought to study harder.
They do not take – S in 3rd. person singular: It may rain, he can dance.
They do not use do / does to form negative, interrogative or short answers: May I come in ? Of course! you may.
They only have one form. Therefore, to express different tenses sometimes we need other verbs with similar meanings:
He is only five, and he can speak German but in the future he will be able to speak German, French & English.

3. USES : Many modal verbs have several different meanings,
depending on their context.
Let’s see some of them:

4. Ability & Permission:
can
could
be able to
be allowed to

5. Permission Usage Examples
Use 'can' or 'be able to' to express an ability or possibility
NOTE: The future of 'be able to' is 'will be able to
He can play tennis well.
She is able to speak five languages.
They can come on Friday.
Jack will be able to come next week.
Could in the past means the general ability to do something.
He could swim when he was five.
IMPORTANT: If someone was in the position to do something, or managed to do something, we use 'was/were able to instead of 'could'
In the negative,' wasn't able to' OR 'couldn't' are both correct.
They were able to get tickets for the concert.
I was able to finish before 6.
I couldn't come last night, sorry. OR I wasn't able to come last night, sorry.

6. USES
Can is used to talk about ABILITY in the present : I can play the piano quite well.
Could is used to talk about Ability in the past: When I was young I couldn’t play piano.
We use BE ABLE TO in other tenses : My daughters will be able to play piano much better than me.
Can is used to talk about PERMISSION in the present: Can I leave the room?
Could is used to talk about Permission in the past :In summer, we could go out till late at nights.
We use BE ALLOWED TO (which is not a modal verb)to talk about Permission in other tenses : I’ve never been allowed to smoke.
We use MUSTN’T to express a strong Prohibition: You musn’t smoke in here. It is illegal.

7. POSSIBILITY & DEDUCTION
may
might
can
could
must

8. POSSIBILITY & DEDUCTION
Examples
Usage
They must be in Spain by now.
She must have done well on the test.
Use 'must' plus the verb when you are 100% (or almost 100%) sure that something is the case.
She might come this evening.
David may invite Jesica to the match.
Jack might have gone to France.
Use 'might' or 'may' to express an opinion that you think has a good possibility of being true.
Jane could be at work.
Peter could have arrived late.
Use 'could' to express a possibilty which is one of many. This form is not as strong as 'might' or 'may'. It is just one of a number of possibilities.
You can't be serious!
They can't have worked until late.
Use 'can't' to express an opinion that you are 100% sure is NOT true.
Notice that the past form remains 'can't have done'

9. POSSIBILITY & DEDUCTION
Mary's late.

10. POSSIBILITY & DEDUCTION
She might be ill.
She may be ill.
She could be ill.

11. POSSIBILITY & DEDUCTION
can
could
base form
may
might

12. POSSIBILITY & DEDUCTION
She's never late.

13. POSSIBILITY & DEDUCTION
She must be ill.
I'm sure.

14. POSSIBILITY & DEDUCTION
No, I'm sure that's not true.
She can't be ill.

15. POSSIBILITY & DEDUCTION
She can't be ill.
now
She must be playing tennis.

16. USES:
We use may, may not, might, might not and could to imply present or future Possibility : It might rain.
I could pass the exam.
he may come late.
We use can’t when we believe or guess something is impossible:
It can’t be true.
We use must and can’t when we make a logical deduction :
He must be very rich, he’s got his own plane.
That house can’t be very cheap, it’s got two floors and a garden.

17. OBLIGATION & NECESSITY
must
have to
need
should
ought to
had better

18. USES :
We use must (or have to ) to talk about obligation : All students must do the exam.
We use needn’t (or don’t have to ) when there is NO obligation : you needn’t do (= don’t have to do) the exam, you have passed.
Need (without TO ) is only used in negat & interrogat. ss. In affirmative ss, we use need to to express necessity: We need to find a solution to this problem.

19. USES :
We use ought to, should,and shouldn’t to give advice and give recomendations: Students ought to study.
You shouldn’t smoke.
Had better is similar to should & ought to (intention and advice)
I’d better give up smoking.
He is not feeling very well. He had better NOT go go out.
Now ty this exercise

20. Obligation and necessity
Necessary? Not necessary?
In my country…
You
wear seat bealt in a car
Men
do military service
Children
go to school on Saturday
go to the doctor every year
pay for school books.
vote in an election
pay to drive on motorways
must
needn’t
needn’t
should
have to
should
have to

21. PERFECT MODALS of MODAL VERBS
We can use some modal verbs with
HAVE + Past Participle to talk about past events.
Let’s see:

22. MUST HAVE + PP
We use must have +pp to express a certainty or to make a logical deduction about the past.
He must have worked hard. He got a very good mark.
Tom was late. He must have had some problems.

23. CAN’T HAVE + PP
Can’t have + pp is used to express an impossibility in the past.
You can’t have read the book yet . It’s too thick.
He can’t have been ill. I saw him yesterday

24. MIGHT / MAY / COULD HAVE+PP
We use might / may / could have + pp to express a possibility in the past:
She may have lost her purse.
He could have asked the wrong question.

25. SHOULD HAVE + PP
We use should have + pp to give an opinion about past events, even though it is now too late:
They should have saved the changes before.
He should have been more patient.

26. COULD HAVE + PP
We use could have + pp to suggest an alternative past action, even though it is now too late:
They could have told me about his illness.
You could have waited for me.

27. SHOULDN’T HAVE + PP
We use shouldn’ t have + pp to express regret or criticism about past events:
He shouldn’t have cheated in the exam
You shouldn’t have spoken in such a way

28. Giving advice Write what they should or shouldn’t have done
He should have taken a map.
He shouldn’t have forgotten his map.

29. Giving advice He should have watched out his bag
He shouldnt’t have left his bag alone.

30. Giving advice He should have studied languages
He shouldn’t have missed his language lessons

31. Let’s do some exercises:
Ted's flight from Amsterdam took more than 11 hours. He be exhausted after such a long flight (must/can/had better)
The book is optional. My professor said we could read it if we needed extra credit. But we read it if we don't want (mustn’t/can’t /don’t have to)
Susan hear the speaker because the crowd was cheering so loudly (might not/ couldn’t/ can’t)
The television isn't working. It damaged during the move (must have been/must be / must)
Kate: hold your breath for more than a minute? Jack: No, I can't (might you / are you able/ can you)
You be rich to be a success. Some of the most successful people I know haven't got a penny to their name. (can’t/shouldn´t /don't have to)
I've redone this math problem at least twenty times, but my answer is wrong according to the answer key. The answer in the book be wrong! (must/should/have to)
must
Don’t have to
couldn’t
must have been
Can you
don't have to
must

32. Let’s try again:
You do the job if you didn't speak Japanese fluently. (won't be able to /can/ couldn't)
You worry so much. It doesn't do you any good. Either you get the job, or you don't. (shouldn't /can’t/ don't have to)
You be kidding! That can't be true (should / have to / ought to )
You leave the table once you have finished your meal and politely excused yourself may / might / would)
Jenny's engagement ring is enormous! It a fortune (must have cost / must cost /must be costing)
If I had gone white water rafting with my friends, I down the Colorado River right now. (would be floating /would float /would have floated)
You take along some cash. The restaurant may not accept credit cards. (had better/has to /can)
The machine on by flipping this switch (may turned / can be turned /could be turning)
couldn't
shouldn't
have to
may
must have cost
would be floating
Had better
can be turned