Let’s Learn Modal Verbs

Modal verbs are special verbs that help express a speaker’s attitude or opinion. Modal verbs are verbs that express necessity, possibility, permission, ability, obligation, advice, expectation and deduction. The main modal verbs in English are: can could, may, might, must, have to, should, ought to, need.

The Types of Modal Verbs

Ability: can, could, be able to

Can and cannot/can’t are often used to express ability in the present.

She can speak three languages.
He can’t rollerblade.
Can you sepak Italian?

Could or could not/couldn’t are often used to express past ability:

When I was younger, I could run fast.
I couldn’t read when I was four.

Be able to + infinitive can be used instead of can to talk about ability but be able to is more formal and is not as common.

We can use can and be able to to talk about general ability in the present.

She can speak Japanese. She’s able to speak Japanese.
She can knit. She’s able to knit.

We can use could and be able to to talk about general ability in the past.

My son could walk when he was 11 months old.
My son was able to walk when he was 11 months old.

But if we want to say that someone did something in a specific situation, we must use was/were able to, or managed to + infinitive.

There was a fire, but all the workers were able to/managed to escape.
He didn’t have an address, but he was able to/managed to find the place.

In negative sentences, both could and be able to can be used to say that we were not capable of doing something on a specific occasion.

It was very dark, and they couldn’t find the exit.
It was very dark, and they weren’t able to find the exit.

Possibility: may, might

It may rain later.
He might come to the party.
They might go to Italy.
He might not be here next week.
I might not have time to go out.

Permission: can, may, could

Can is used for informal permission. May is used for formal permission. If we want politely request for permission, we use could.

Can I leave early today?
Can I sit here?
You can use my car if you like.
Can I make a suggestion?
May I use your phone?
May I see your passport, please?
Could I ask you something?
Could I interrupt?
Could I borrow your car?

Obligation: must, have to

We use have to and must to express obligation. There is a slight difference between the way we use them. Must expresses strong obligation or necessity. It often shows us that the obligation comes from the speaker (or the authority that wrote the sentence). Have to also expresses obligation. Have to shows us that the obligation comes from outside the speaker. We call this ‘external obligation’. We don’t use must to express obligation in the past. We use have to instead.

You must wear a seatbelt.
I must phone my mum. It’s her birthday today.
I have to finish my homework by tomorrow.
A bus driver has to have a driving licence.

Prohibition: mustn’t, can’t

Must not/mustn’t expresses strong prohibition. We use it in order to show that something is prohibited or not allowed. It is common on public signs and notices informing people of rules and laws. We use mustn’t particularly when the prohibition comes from the speaker.

You must not smoke here.
Visitors must not park in the staff car park.
Baggage mustn’t be left unattended.
Guests mustn’t make noise after 10 p.m.
(Parent to child) You mustn’t say things like that to your sister.
(Teacher to student) You mustn’t be late to class.
I mustn’t let that happen again.

Cannot/can’t expresses prohibition or impossibility. We use can’t to talk about something that is against the rules, particularly when we didn’t make the rules.

What does this sign say? Oh, we can’t park here.
You can’t take photos in the museum. They’re really strict about it.
Sorry, we can’t sell knives to under-18s.

Necessity: must, have to, have got to, need to

Must expresses a strong necessity. It is the strongest of these modal verbs and is most common in writing. We usually don’t use must in questions. Have got to is most common in informal speech. It is not used in questions. Have to is the most commonly used modal of obligation. It is useful for forming questions and negatives. There is only one way to express past time with these modal verbs: had to. There is no past tense of must and have got to. Need to expresses necessity, often in a practical sense. The verb need is a semi-modal. It is a normal verb and also a modal verb. It uses the auxiliary verb do to form the negative form.

You must see this movie.
I have got to study tonight.
You need to renew your passport.
They had to get up early yesterday.
Did you have to work last weekend?

Lack of Necessity: don’t have to, don’t need to, needn’t

Don’t have to indicates that something is not necessary. Needn’t or don’t need to expresses lack of necessity.

You don’t have to go if you don’t want to.
I didn’t have to do the laundry last night.
You needn’t worry about it.
You don’t need to bring your textbook for the lesson.

Advice: should, ought to

Should offers advice. Ought to is similar to should but slightly stronger.

You should take an umbrella.
You ought to see a doctor.
She should keep to a healthy diet.
They shouldn’t drink so much coca cola.
You ought not go to bed so late.

Expectation: should, ought to

Should expresses expectation. Ought to expresses a strong expectation.

They should arrive by noon.
He ought to be here by now.
Helen should be in London by next week. Her new job starts on Monday.

Deduction or specultaion: must, can’t, may, might, should, ought to

Modal verbs of deduction are used to express how certain we are about something, based on the information we have. They allow us to speculate or make guesses and conclusions about past, present, or future situations.

Deduction about the Present

Must indicates a strong degree of certainty (almost sure) that something is true.
Can’t/cannot indicates a strong degree of certainty that something is not true.
Might/may/could indicate possibility but with less certainty (not sure).

She must be at work; her car isn’t in the driveway.
He can’t be the thief; he was with me the entire time.
She might be at home, but I’m not sure.
He could be the one who left the door open.

Deduction about the Past

Must have + past participle indicates a strong degree of certainty that something happened.
Can’t/Couldn’t have + past participle indicates a strong degree of certainty that something didn’t happen.
Might/May/Could have + past participle indicate that something possibly happened, but with less certainty.

She must have forgotten about the meeting.
He can’t have finished the project so quickly; it’s too difficult.
She might have left her phone at home.
They could have taken the wrong train.

Deduction about the Future

Should indicates an expectation based on evidence or logic. Ought to is similar to should, indicating a strong expectation.

The package should arrive tomorrow.
They ought to finish the work by next week.

Have Practice Using Modal Verbs

Task 1. Modal verbs for obligation, prohibition and advice: must, have to, ought to, should. Complete the text using the correct forms of the words:

have to don’t have to must mustn’t should shouldn’t

Text 1

Hi! I’m Harry and my school is organising a camping trip soon for all the students. We 0 have to get permission from our parents first, of course, before we can go. I’m not sure if I 1_____________ go or not, and my parents have said I 2_____________ if I don’t want to. But I guess I 3_____________ just stay at home and miss all the fun! We’ll 4_____________ take our own clothes to wear, but luckily we 5_____________ take tents, because they’re provided. I 6_____________ remember to take a warm jacket, though, as it will be chilly. And the teachers have said we 7_____________ take our mobile phones in case they get lost! It’s not allowed! I’d really like to have my phone with me – but at least this means I 8_____________ ring my parents every night to say that I’m OK!

Text 2

Hi! I’m Naomi and my school is organising a climbing trip soon for all the students. We 0 have to get permission from our parents first, of course, before we can go. My teacher has said we 1_____________ go if we don’t want to, but I feel I really 2_____________ try it, just for a new experience! But I’ve realised I’m not fit enough, so I absolutely 3_____________ do some training first. I 4_____________ do anything stupid, though, or I’ll injure myself! So I’ve joined a fitness training class after school. The trainer advised us that we 5_____________ try to do anything too challenging, as that can cause injuries, and we 6_____________ prepare to go mountain climbing after a few weeks! At the moment, we 7_____________ go twice a week, but luckily we 8_____________ go at the
weekends, so I just rest then!

Task 2. Complete the second sentence so that it means the same as the first using the correct form of modal verbs should, must, have (to) or ought (to).

Example: Don’t talk in the library! It’s not permitted. – You mustn’t talk in the library.

You need to try and eat more fruit, if you can. You _________________ try and eat more fruit.
It’s not allowed to take photos here. You _________________ take photos here.
It’s a good idea to see the doctor about your injured leg, I think. I think you _________________ to see a doctor about your injured leg.
Don’t let me forget to ring my grandma this evening. I _________________ ring my grandma this evening.
Dad’s a doctor, so he works at weekends. He has no choice. Dad’s a doctor, so he _________________ work at weekends.
It’s not necessary to run. We’ve got time. We _________________ run.
I don’t think it’s a good idea to eat lots of chocolate before dinner. You _________________ eat lots of chocolate before dinner.
There’s no school tomorrow, because it’s a school holiday. We _________________ go to school tomorrow, because it’s a holiday.
My coach has advised me to try and go to football practice twice a week, if I can. I _________________ to go to football practice twice a week, if I can.
Please remind me to post this letter! I _________________ forget to post this letter!
If we don’t run for the bus, we’ll miss it! We’ll _________________ run for the bus!
It’s a weekday, so my brother shouldn’t be at home now. It’s a weekday, so my brother _________________ to be at work now.
Do come and see our new puppy – he’s wonderful! You _________________ come and see our new puppy!
I’ve done a lot of maths practice, so I don’t think I need to work too hard for next week’s test. I _________________ need to work too hard for next week’s test.

Task 3. Modal verbs for speculation: must, could, might/may, can’t. Choose the correct options to complete the sentences.

Example: Tom’s walked a really long way today. He must / might / can’t be tired.

Take an umbrella with you because it may / can’t / must rain later.
Ben always gets 100% in his Maths tests. He can’t / could / must be clever.
The phone’s ringing. It must / can’t / might be Mum, because she never rings when she’s at work.
I’m not sure what’s in this cake. It could / must / can’t be coconut.
There’s someone at the door. It can’t / might / must be Alan. I’m expecting him to arrive now.
I’m going to buy this book. I think it must / may / can’t help with my school project.
Jack said he’s at home tonight. That must / may / can’t be true. I’ve just seen him in town!
Tom’s planning to buy a skateboard, a phone and a laptop. He must / might / can’t have a lot of money.
I don’t know where Sam is. He must / can’t / could be in his room, I guess.
Karen goes into town every morning. It’s 10 am, so she can’t / may / must be there now.
Sarah spent all her birthday money in town yesterday, so she must / might / can’t have any money left.
Take a jacket, because it must / may / can’t be chilly this evening. This looks like a luxury hotel. It must / might / can’t be very cheap to stay there.
I’m not sure who this bag belongs to. It must / could / can’t be Ryan’s, I suppose.
It must / might / can’t be raining outside. People are walking around with their umbrellas up.
I wonder if this suitcase will be OK for my holiday? The problem is, it can’t / might / must be too heavy for me to carry.

Task 4. Complete the second sentence so that it means the same as the first, using modal verbs must, can’t or might/may/could.

Example: I’m sure Dad’s tired. He’s been at work all day. – Dad must be tired. He’s been at work all day.

I’m not sure but it looks like snow falling outside. It _________________ snow falling outside.
Karl isn’t asleep – he’s singing upstairs in hisroom. Karl _________________ asleep. He’s singing upstairs in his room!
I don’t know who’s in this photo – maybe Ted’s family? It _________________ Ted’s family in the photo.
This looks like my book, but it hasn’t got my name in it. This _________________ my book as it hasn’t got my name in it.
I’m sure my bag’s on the table. I left it there! My bag _________________ on the table – I left it there!
Who’s the person with Billy? Perhaps it’s his sister. The person with Billy _________________ his sister.
I’m sure this is where Dan lives – 20 Main Street. This _________________ where Dan lives – 20 Main Street.
I’ve got a map, but perhaps it’s out of date. I’ve got a map, but it _________________ out of date.
I’m sure these aren’t my keys. Mine are in my bag. These _________________ my keys, as mine are in my bag.
Is John at work today? I’m not sure. John _________________ be at work today.
This isn’t Anna in the photo, is it? Anna’s hair is blond, not dark. This _________________ Anna in the photo.
Paul’s staying in a tent this week. I’m sure he’s cold. Paul _________________ cold in his tent!
Perhaps Harry is already travelling to work. Harry _________________ on his way to work.
I’m sure that Matt’s going on holiday soon. Here’s his ticket! Matt _________________ going on holiday soon.
Choose the correct options to complete the
sentences.

Task 5. Choose the correct options to complete the sentences.

My mum’s a doctor, so she often must / has to work at weekends.
You mustn’t / shouldn’t drive fast here – there’s a speed limit!
There’s a good train service to the city, so we mustn’t / don’t have to drive there.
You ought / should to go to the doctor about your sore leg.
In England, drivers have to / should drive on the left.
You shouldn’t / don’t have to pack lots of heavy things in your bag.
It’s my grandma’s birthday today, so I must / ought to ring her this morning.
We must / mustn’t forget to take towels to the beach.
I think you should / shouldn’t ask your teacher for help with your homework.
I must / don’t have to write and thank my grandparents for my birthday presents.
The train leaves at 6, so we mustn’t / ought to be late.
You should / have to go for a run if you want a bit of exercise.
Everyone ought / should to try and eat lots of fruit and vegetables every day.
We’ve got plenty of time, so we don’t have to / mustn’t run.
You mustn’t / don’t have to be cross with your mum. She was just trying to help.
Do you have to / Should you wear school uniform at your school?
This cake is really stale, so you should / shouldn’t eat it.

Task 6. Complete the sentences below using modal verbs must, can’t or might.

This bag ______ belong to Karen. It’s got her name on it.
That ______ be Sam calling me. He’s in Australia – and it’s the middle of the night there!
I’m not sure what we’re doing tomorrow – we ______ go to the beach.
My money ______ be in my purse. I put it in there this morning.
Dad said he ______ take us swimming later, if he’s got time.
That ______ be the bus to the centre. It says City on it.
Ali isn’t at school this morning, but I’m not sure.
Take an umbrella with you. It ______ rain later.
This ______ be my book. My brother’s homework is inside it!
That _______ be Sarah ringing. She promised to call this evening.
I’m not sure where Dad is. He ______ be in the garden, or maybe in the garage.
This photo ______ belong to John. I’m sure that’s him and his family!
The train station ______ be this way, but I’m not sure.
It ______ be 5 o’clock already! I’ve only just got home from school!