This document provides information on modal auxiliary verbs in English. It discusses the features of modal verbs, including that they are invariable and defective since they lack certain verb tenses. It then defines and provides examples of usage for various modal verbs, including can, can't, could, be able to, may, might, must, mustn't, have to, need to, don't have to, mustn't, would, should, and ought to. It compares the uses of must and have to as well as should and ought to.

1. MODAL AUXILIARYMODAL AUXILIARY
VERBSVERBS
FEATURESFEATURES
-INVARIABLEINVARIABLE
- AUXILIARY, NOT MAIN VERBSAUXILIARY, NOT MAIN VERBS
-DEFECTIVE SINCE THEY LACK CERTAINDEFECTIVE SINCE THEY LACK CERTAIN
VERBAL TENSES (NO INFINITIVE, NOVERBAL TENSES (NO INFINITIVE, NO
GERUND, ETC.)GERUND, ETC.)
- FOLLOWED BY INFINITIVE WITHOUTFOLLOWED BY INFINITIVE WITHOUT
TO.TO.

2. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
CANCAN
- Ability: I can play the guitar.Ability: I can play the guitar.
- Request: Can you pass me the salt, please?Request: Can you pass me the salt, please?
- Permission: Can I go to the toilet, please?Permission: Can I go to the toilet, please?
- Possibility: You can ski in Sierra Nevada in AprilPossibility: You can ski in Sierra Nevada in April
- Suggestion: You can buy me a drink.Suggestion: You can buy me a drink.

3. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
CAN’TCAN’T
- Inability: I can’t play the piano.Inability: I can’t play the piano.
- Prohibition: You can’t go out after 12 am.Prohibition: You can’t go out after 12 am.
- Negative deduction: He can’t be old enough to drive.Negative deduction: He can’t be old enough to drive.
- Impossibility in the past with the structure CAN’TImpossibility in the past with the structure CAN’T
HAVE + PAST PARTICIPLE: He can’t have been atHAVE + PAST PARTICIPLE: He can’t have been at
home yesterday because I phoned him serveral times.home yesterday because I phoned him serveral times.

4. EXPRESSIONS WITH CAN’TEXPRESSIONS WITH CAN’T
- He can’t help … (No puede evitar …)He can’t help … (No puede evitar …)
- I can’t stand / I can’t bear … (noI can’t stand / I can’t bear … (no
aguanto/ no soporto …).aguanto/ no soporto …).
Examples:Examples:
He can’t help being stupid.He can’t help being stupid.
I can’t stand rock music.I can’t stand rock music.

5. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
COULDCOULD
- Past ability: I could swim when I was four.- Past ability: I could swim when I was four.
- Polite request: Could you pass me the salt,- Polite request: Could you pass me the salt,
please?please?
- Polite suggestion: You could visit your aunt from- Polite suggestion: You could visit your aunt from
time to time.time to time.
- Possibility: John could pass his driving test.- Possibility: John could pass his driving test.

6. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
COULDCOULD
- Deductions when we are not sure something isDeductions when we are not sure something is
true: I’m not sure but that could be Tom’s mum.true: I’m not sure but that could be Tom’s mum.
- Impossibility in the past (couldn’t have +p.p.):Impossibility in the past (couldn’t have +p.p.):
He couldn’t have done his homework soHe couldn’t have done his homework so
quickly.quickly.

7. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
BE ABLE TOBE ABLE TO
- Ability (for the other tenses where you can’t useAbility (for the other tenses where you can’t use
CAN & COULD):CAN & COULD):
- You’ll be able to play next football match.You’ll be able to play next football match.
- I’ve been able to play this football match.I’ve been able to play this football match.
- I was able to run 1000 metres in under 3I was able to run 1000 metres in under 3
minutes.minutes.

8. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
MAYMAY
- Possibility: It may be true. (Puede que seaPossibility: It may be true. (Puede que sea
verdad / Puede ser cierto).verdad / Puede ser cierto).
- Ask for and give permission: May I come in?Ask for and give permission: May I come in?
Yes, you may.Yes, you may.
( COULD is more polite than MAY; MAY is( COULD is more polite than MAY; MAY is
more polite than CAN).more polite than CAN).
MIGHTMIGHT
- Remote possibility: It might rain tomorrow.- Remote possibility: It might rain tomorrow.

9. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
MUSTMUST
- Obligation, strong necessity: I must go to schoolObligation, strong necessity: I must go to school
every day.every day.
- Affirmative deduction: She must be 20.Affirmative deduction: She must be 20.
- To give instructions: Patients must take theirTo give instructions: Patients must take their
medicine every day.medicine every day.
- Possibility in the past when we are surePossibility in the past when we are sure
something happened (must have + p.p.): He’s atsomething happened (must have + p.p.): He’s at
home. He must have taken a taxi.home. He must have taken a taxi.

10. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
MUSTN’TMUSTN’T
Prohibition: You mustn’t smoke in public places.Prohibition: You mustn’t smoke in public places.
HAVE TOHAVE TO
- Everyday obligations or necessities: I have to get
up early in the morning.
- Obligations imposed by others: I have to be
home before midnight. Otherwise, my parents
will be mad at me.

11. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
MUST vs HAVE TOMUST vs HAVE TO
MUST: no suele utilizarse en interrogativa. Se trata de unMUST: no suele utilizarse en interrogativa. Se trata de un
deber impuesto por la persona que habla; implica adeber impuesto por la persona que habla; implica a
veces el cumplimiento de normas, de leyes (Soldiersveces el cumplimiento de normas, de leyes (Soldiers
must obey their captain). A veces la obligación conmust obey their captain). A veces la obligación con
MUST tiene el sentido de recomendación o consejoMUST tiene el sentido de recomendación o consejo
(You must visit the British Museum in London).(You must visit the British Museum in London).
HAVE TO: obligación impuesta por una persona oHAVE TO: obligación impuesta por una persona o
circunstancias externas. No implica el cumplimiento decircunstancias externas. No implica el cumplimiento de
ninguna norma.ninguna norma.
They’ll have to hurry because shops close at 10 o’clock.They’ll have to hurry because shops close at 10 o’clock.

12. MODAL AUXILIARY VEBSMODAL AUXILIARY VEBS
NEED TONEED TO
- Not a modal verb per se but used in theNot a modal verb per se but used in the
affirmative form to convey OBLIGATION oraffirmative form to convey OBLIGATION or
NECESSITY.NECESSITY.
- You need to study hard in order to pass all yourYou need to study hard in order to pass all your
examinations.examinations.

13. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
NEEDN’T TO ---DON’T/ DOESN’T /NEEDN’T TO ---DON’T/ DOESN’T /
DIDN’T NEED TODIDN’T NEED TO
- Lack of obligation or necessity:Lack of obligation or necessity:
It’s only eight o’clock, we needn’t hurry /we don’tIt’s only eight o’clock, we needn’t hurry /we don’t
need to hurr / We didn’t need to wait. There was noneed to hurr / We didn’t need to wait. There was no
queue.queue.
Son sólo las ocho. No tenemos que darnos prisa.Son sólo las ocho. No tenemos que darnos prisa.
NEEDN’T HAVE + PAST PARTICIPLENEEDN’T HAVE + PAST PARTICIPLE
To say we did something in the past although it wasn’tTo say we did something in the past although it wasn’t
necessary.necessary.
I needn’t have come to school. The teacher was ill andI needn’t have come to school. The teacher was ill and
there were no lessons.there were no lessons.

14. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
DON’T HAVE TODON’T HAVE TO
- Lack of obligation or necesity, that is,Lack of obligation or necesity, that is,
absence of legal rule.absence of legal rule.
You don’t have to wear tie (No hay queYou don’t have to wear tie (No hay que
llevar corbata)llevar corbata)
MUSN’TMUSN’T
- Prohibition: You mustn’t smoke in class- Prohibition: You mustn’t smoke in class
(No debes/Está prohibido …).(No debes/Está prohibido …).

15. MODAL AUXILIARY VEBSMODAL AUXILIARY VEBS
WOULDWOULD
- Invitations/Offers: Would you like something toInvitations/Offers: Would you like something to
drink? ¿Le gustaría ..?drink? ¿Le gustaría ..?
- Formal request: Would you help me, please?Formal request: Would you help me, please?
¿Podría ayudarme, por favor?¿Podría ayudarme, por favor?
SHOULDSHOULD
- Advice: You shouldn’t eat too much.Advice: You shouldn’t eat too much.
- Moral obligation: Children should look afterMoral obligation: Children should look after
their parents when they are old.their parents when they are old.

16. MODAL AUXILIARY VEBSMODAL AUXILIARY VEBS
OUGHT TOOUGHT TO
- Advice, weird in negative and interrogativeAdvice, weird in negative and interrogative
sentences.sentences.
You ought to work harder.You ought to work harder.
- Criticism of past actions with the structure- Criticism of past actions with the structure
OUGHT TO HAVE + PAST PARTICIPLEOUGHT TO HAVE + PAST PARTICIPLE
(SHOULD also posible).(SHOULD also posible).
He ought to have studied more for theHe ought to have studied more for the
exam.exam.
He should have studied more for the examHe should have studied more for the exam..

17. MODAL AUXILIARY VERBSMODAL AUXILIARY VERBS
SHOULD vs OUGHT TOSHOULD vs OUGHT TO
Utilizaremos SHOULD a la hora de dar un consejoUtilizaremos SHOULD a la hora de dar un consejo
personal o de señalar que una opción es mejor que otra.personal o de señalar que una opción es mejor que otra.
- We should visit her.We should visit her.
- We shouldn’t wear only a T-shirt. It’s cold.We shouldn’t wear only a T-shirt. It’s cold.
Si SHOULD expresa una opinión subjetiva, OUGHT TOSi SHOULD expresa una opinión subjetiva, OUGHT TO
alude a una idea generalizada y externa de que algo noalude a una idea generalizada y externa de que algo no
es recomendable.es recomendable.
- You ought not to smoke.- You ought not to smoke.