Modal Verbs

MODAL VERBS

What are modal verbs?

When do we use modal verbs?

What are the rules for modal verbs?

1. SAME FORM FOR ALL SUBJECTS

Iyou he she must it we they

He musts

2. NO AUXILIARY VERB FOR NEGATIVE AND INTERROGATIVE FORMS

I should...

I shouldn't...

or... should I?

They don't can... Does she must?

3. MODALS ARE FOLLOWED BY THE INFINITIVE WITHOUT TO (BASE FORM) OF THE MAIN VERB

I must to go now

EXCEPTIONS!!!!

4. THEY ONLY HAVE PRESENT OR PAST TENSE

INFINITIVE

PRESENT

PAST

PAST PARTICIPLE

been

was/were

to be

am/is/are

can

could

must

should

shall

may

might

would

will

ABILITY

CAN/CAN'T/COULD/BE ABLE TO

• I can jump high

• Jack can't swim (inability)

• I could do it easily (past ability)

• She wasn't able to finish the exam (inability)

PERMISSION & LACK OF PERMISSION or PROHIBITION

CAN/CAN'T COULD/COULDN'T MUST/MUSTN'T BE ALLOWED TO/ NOT BE ALLOWED TO MAY/MIGHT

• Can I sit here? (informal; asking for permission)
• You can’t sit here (refusing permission)
• Could I use this chair? (more formal and polite)
• He couldn’t sit down during the lesson.
• You mustn't cycle on the foot path (it's forbidden)
• He is allowed to go to the party (permission)
• Students are not allowed to smoke at school (prohibition)

• You may use this chair (formal; giving permission)
• Might/May I use this chair? (more formal and polite; asking for permission)

• Sorry, you may not / might not use this chair (formal; refusing permission)

OBLIGATION & PROHIBITION

MUST/MUSTN'T HAVE TO/ DON'T HAVE TO

But... what is the difference???

Have to is a normal verbMust is a modal verb

PRESENT

PAST PARTICIPLE

INFINITIVE

PAST

had to

have/has to

had to

to have to

must

Have to: external obligations (for what somebody in authority has said it is necessary to do; facts, not opinions). Must: personal obligations (for more personal opinions about what it is necessary to do)

• She must talk to you about her secret (it's important for the speaker's opinion/feelings)
• You mustn't skip a traffic light (it expresses prohibition)

• You have to be eighteen to get your driving licence (it's a law)
• Do you have to wear a tie to work? (asking about work rules)
• He doesn't have to go there (lack/absence of obligation/necessity)

NECESSITY & LACK OF NECESSITY

NEED TO/ DON'T NEED TO OR NEEDN'T

• You need to eat more vegetables to stay healthy (it's necessary)

• I can hear you! You don't need to shout (it is not necessary)
• I can hear you! You needn't shout

PROBABILITY/POSSIBILITY

MAY/MIGHT/COULD

to say that sth is possible, but not certain

• They may come by car. (Maybe they will come by car.)

• They might be at home. (Maybe they are at home.)

• If we don't hurry, we could be late. (Maybe we will be late.)

• It might rain today

• Jack may be coming for your birthday party

REQUESTS/OFFERS & INVITATIONS

CAN/COULD WILL/WOULD SHALL

• Could you take a message, please?

• Can you take a message, please? (less polite)
• Would you carry this for me, please?
• Will you carry this for me, please? (less polite)
• Can I do that for you? (offer)
• Shall I call you on your mobile?
• I could give you a lift to the station.
• I'll do that for you if you like.
• Would you like to come round tomorrow? (invitation)
• Would you like another drink?

SUGGESTIONS & ADVICE

SHOULD/ SHOULDN'T OUGHT TO COULD

• You should send an email
• You shouldn’t go by train
• There should be more street lights here
• There ought to be more street lights here
• Could you get an earlier train?

COMPLETE

_____ we bake a cake? I ______ work out once a week.You _____ do your homework.I ______ go to the doctor tomorrowWhen I was younger I ______ climb a tree. Susan ____ arrive earlier. I_______ practice a lot to improve my speaking skills. We ___ be in United States soon.

To be continued...

PRESENT SPECULATION

MUST MAY/MIGHT/COULD CAN'T

Modal verb + infinitive without to of the main verb

MUST

We are certain or almost certain that sth is true

Mary's hair is wet. It must be rainy. Come inside and get warm. You must be freezing out there!

MAY/MIGHT/COULD

To talk about possibility (we think sth is possible, but we're not certain)

I make some guesses

Jane is late for work...

• Her car could be broken.
• She might still be asleep.
• There may be a lot of traffic.

CAN'T

We are certain that sth is not possible

It can't be easy for her, looking after three kids on her own.

That can't be true. You cannot be serious.

PAST SPECULATION

MUST HAVE MAY/MIGHT/COULD HAVE CAN'T HAVE

Modal verb + have + the past participle of the main verb

MUST HAVE

We are certain or almost certain that sth was true or happened

You look happy. You must have heard the good news. We've got ice-cream! Mum must have bought some yesterday.

MAY/MIGHT/COULD HAVE

we think it's possible that sth happened

I make some guesses about the past

I haven't received your package. It may have got lost in the post. I think I might have left the air conditioning on. Please can you check? Where are they? They could have got lost.

CAN'T HAVE

to say that a past event was impossible (we think it's not possible that sth happened).

They know the way here. They can't have got lost!

I thought I saw Sam this morning but it couldn't have been him! He's in Greece this week.