This document defines and categorizes modal auxiliary verbs. It begins by defining modal verbs as verbs that accompany other verbs and add abstract meanings like obligation or permission. It then lists the main English modal verbs and groups them based on whether they express a single concept or double concept. The document also categorizes modal verbs based on the meanings they express, such as ability, obligation, possibility, and certainty. It concludes by explaining how modal verbs are used with perfect infinitives to discuss past possibility, certainty, or advice.

1. MODAL AUXILIARY VERBS
By JESÚS HERRERO

2. MODAL AUXILIARY VERBS
 DEFINITION
 LIST
 STRUCTURE
 GROUPS
 PERFECT MODALS

3. DEFINITION

4. MODAL AUXILIARY VERBS
DEFINITION
1. They are part of the verbal phrase:
I must get there before 7 o'clock.
must get
2. They always accompany, assist or help
other verbs.
3. They add abstract (modal) meanings like
obligation, permission, advice, etc

5. LIST OF MODAL VERBS

6. LIST OF MODAL VERBS
can could
*be able to must
*have to need
should *ought to
may might

7. MODAL VERBS STRUCTURE

8. MODAL VERBS STRUCTURE
1. How do we use modal verbs?
• Affirmative: subject + modal + base form
ex. She should stay
• Negative: subject + modal(n't) + base form
ex: She shouldn't stay
• Interrogative: (Wh)Modal + subject +base
form?
ex: Why should she stay?

9. MODAL VERBS STRUCTURE
2. Modal verbs are used with infinitives without
to (bare infinitives or base form) with the
exception of ought to:
We must get there before 7 o'clock.
She should study harder.
I ought to go home now.
(Have to is studied with modal verbs but it's not
a pure modal verb as it needs auxiliary verbs
and has -s in the third person singular)

10. MODAL VERBS STRUCTURE
3. Modal verbs do not add -s or -es to the third
person singular. They are invariable verbs.
He can swim.
He cans wim

11. MODAL VERBS STRUCTURE
4. They don't need auxiliaries to form short
answers or negative and interrogative
sentences:
She shouldn't eat salt.
She doesn't should eat salt
May I help you? Yes, you may.
Do I may help you? Yes you do
5. They do not have infinitives or -ing forms.
*canning *to might

12. MODAL VERBS STRUCTURE
6. Modal verbs do not have all the tenses.
They use other verbs to complete the
tenses:
can > could, be able to
They can swim now > She will be
able to swim next year
must > had to
You must come early > You had to
come early yesterday

13. GROUPS OF MODAL VERBS

14. GROUPS OF MODAL VERBS
We are going to study them from two points of
view:
a. number of meanings or concepts that
they express:
single, double
b. modal meanings that they express:
permission, ability, obligation ...

15. NUMBER OF MEANINGS

16. GROUPS OF MODAL VERBS
(a. number of meanings)
1. The same modal verb can have different
meanings depending on the context.
May I come in? It may rain tomorrow
2. We can make two categories:
a. Single concept modals: These modal
verbs have 1 meaning
b. Double concept modals: They have 2
meanings

17. GROUPS OF MODAL VERBS
(a. number of meanings)
Single concept Double concept
Will May
Might Must
Should Would
Can
Could

18. GROUPS OF MODAL VERBS
(a. number of meanings)
Modal
Single concept modals
Concept Example
Will Future Peter will visit London some day
Might Probability He might see Big Ben
Should Advice He should wear comfortable shoes

19. GROUPS OF MODAL VERBS
(a. number of meanings)
Modal
Double concept modal
Concept Example
May
Permission May I come in?
Probability I may go to London next summer
Must
Obligation Students must wear uniforms
Certainty They must be at home, the lights are on
Would
Conditional I would visit London if I had enough money
Habitual past action When I was a child I would go swimming every day

20. GROUPS OF MODAL VERBS
(a. number of meanings)
Modal
Can
Double concept modal
Concept Example
Could
probability That could be him. He said he'd phone
Past ability I could play the trumpet when I was 10
Permission Students can wear T-shirts
Ability They can swim, they did a course last summer
Can't
Impossible They can't be at home, they left yesterday
No permission They can't be at home, it's not their house

21. MODAL MEANINGS

22. GROUPS OF MODAL VERBS
(b. modal meanings)
Modal verbs express a series of modal
meanings like:
- ability
- obligation
- prohibition
- necessity
- advice
- possibility
- certainty

23. GROUPS OF MODAL VERBS
(b. modal meanings)
ABILITY
(can, could, be able to)
1. Present: can
saben
Two of my friends can play the guitar.
2. Past: could
sabía
When he was a child he could ski well.

24. GROUPS OF MODAL VERBS
(b. modal meanings)
ABILITY
3. Other tenses: be able to
podrán
hemos podido
- Next week they'll be able to vote.
(future)
- We haven't been able to go on holiday
this year. (present perfect)
- We would be able to do it. (conditional)
podríamos

25. GROUPS OF MODAL VERBS
(b. modal meanings)
OBLIGATION
Present: must
Tienen que
Applicants must answer the questions
honestly
Tengo que Tendré que
Other tenses (including present): have to
- I have to study hard this year
- I will have to work hard as a lawyer
- I have had to stay at home lately
He tenido que

26. GROUPS OF MODAL VERBS
(b. modal meanings)
PROHIBITION
We use mustn't to express prohibition
- You mustn't eat too many sweets
- You mustn't cheat in exams
No debes / no puedes

27. GROUPS OF MODAL VERBS
(b. modal meanings)
NECESSITY / NO NECESSITY
Hay que, es necesario que
Affirmative: need to (it's not a modal verb)
You need to do this to pass the subject
Negative: needn't (no obligation) = don't have to
You needn't do it = You don't have to do it
Interrogative: need
Need I do this?
No es necesario

28. GROUPS OF MODAL VERBS
(b. modal meanings)
ADVICE
deberían
You can use ought to, should, shouldn't to
express advice or recommendation.
- Candidates should be friendly
- You shouldn't worry too much about
exams
- Candidates ought to be friendly
No deberías

29. GROUPS OF MODAL VERBS
(b. modal meanings)
POSSIBILITY
Puede que, tal vez
Present & future: may, may not, might,
mightn't, could:
- It may be time for Linda to go
- They might choose Danny
- They could be on the train
Past: may / might / could + have + past perfect
He might have received our message

30. GROUPS OF MODAL VERBS
(b. modal meanings)
CERTAINTY / LOGICAL DEDUCTION
Positive: must
Debe de
It must be quite late, because it's getting
dark
Negative: can't
That can't be true
No puede

31. MODALS + PERFECT
INFINITIVES

32. MODALS + PERFECT
INFINITIVES
When they refer to the past, certain meanings
must be expressed with a modal + perfect
infinitive (have + past participle):
1. certainty / logical deduction
positive, negative
2. possibility
3. advice / recommendation

33. MODALS + PERFECT
INFINITIVES
1. CERTAINTY / LOGICAL DEDUCTION
Positive: must have + past participle
Debió de (haberse)
Danny must have felt disappointed when
he didn't win the prize
No pudo (haber)
Negative: can't have + past participle
She can't have passed the exam, she
didn't study at all

34. MODALS + PERFECT
INFINITIVES
2. POSSIBILITY
When we talk about possibility about the past
we can use: might / may / could + have + past
participle:
-They might not have received our
message
- He may have gone to the cinema
- The government could have acted more
quickly Podría haber / no haber
Puede que haya / no haya

35. MODALS + PERFECT
INFINITIVES
3. ADVICE / RECOMMENDATION
When we express criticism or regret about a
past action we can use should / shouldn't +
have + past participle
- Linda shouldn't have talked so much
- We should have gone to see that film
while it was still on at the cinema
No debería haber / debería haber

36. PRACTICE
Click on this link to practice modal verbs:
http://mimosa.pntic.mec.es/~jherre23/