The main modal verbs that express probability are described here in order of certainty. Will is the most certain, and might/could are the least certain.
Will and won’t are used to predict a future action. The truth or certainty of what is asserted is more or less taken for granted.
e.g. His latest book willbe out next month.
b) Will and won’t are also used to express what we believe or guess to be true about the present. They indicate an assumption based on our knowledge of people and things, their routines, character and qualities.
e.g. Leave the meat in the oven. It won’tbe cooked yet.
It’s Monday morning, so I guess right now Sarah will be taking the children to school.
Must and can’t.
Must is used to assert what we infer or conclude to be the most logical or rational interpretation of the situation. We do not have all the facts, so it is less certain than will. Must in this meaning is not used to speak about the future.
e.g. You say he walked across the Sahara Desert! He must be mad!
You must be joking! I simply don’t believe you!
The negative of this use is can’t.
e.g. She can’t have a ten-year-old daughter! She’s only twenty-one herself!
a) Should expresses what may reasonably be expected to happen. Expectation means believing that things are or will be as we want them to be. This use of should has the idea of if everything has gone according to plan.
e.g. Our guests should be here soon (if they haven’t got lost).
This homework shouldn’t take you too long (if you’ve understood what you have to do).
We should be moving into our new house soon (as long as nothing goes wrong).
b) Should in this use has the idea that we want the action to happen. It is not used to express negative or unpleasant ideas.
e.g. You should pass the exam. You’ve worked hard (NOT You should fail the exam).
4) May, might and could.
a) May expresses the possibility that an event will happen or is happening.
e.g. We may go to Greece this year. We haven’t decided yet.
“Where’s Ann?” “She may be having a bath, I don’t know”.
b) Might and could are slightly more tentative and slightly less certain than may.
e.g. It might rain. Take your umbrella.
You could be right. I’m not sure.
Couldn’t is not used to express a future possibility. The negative of could in this use is might not.
e.g. You might not be right.
d) Couldn’t has a similar meaning to can’t above, only slightly weaker.
e.g. She couldn’t have a ten-year-old daughter! She’s only twenty-one herself!
Modal verbs of probability in the past.
All the modal verbs above can be used with the perfect infinitive to speak about probability in the past. They express the same varying degrees of certainty. Again, will have done is the most certain, and might/ could have done is the least certain.
e.g. “I met a tall girl at your party. Very attractive.” “That’llhave beenmy sister, Patsy.”
It must have been a good party. Everyone stayed till dawn.
The music can’t have been any good. Nobody danced.
Where’s Pete? He should’ve been here ages ago.
He may have got lost.
He might have decided not to come.
He could have had an accident.
Other uses of modal verbs.
Obligation and advice.
Must expresses strong obligation. Other verb forms are provided by have to.
e.g. You must try harder.
You’ll have to do this exercise again.
I hate having to get up early.
Must expresses the opinion of the speaker.
e.g. I must get my hair cut.
You must do this again. (Teacher to student)
Have to expresses a general obligation based on a law or rule, or based on the authority of another person.
e.g. Children have to go to school until they’re sixteen.
Mum says you have to tidy you room.
Mustn’t expresses negative obligation. Don’t have to expresses the absence of obligation.
e.g. You mustn’tsteal. It’s very naughty.
You don’t have to go to England if you want to learn English.
Should and ought to express mild obligation or advice. Should is much more common. Ought to is not used in questions.
e.g. You should go to bed. You look very tired.
You ought to take things easier.
Should (ought to) + the perfect infinitive is used to refer to a desirable action in the past that didn’t happen.
e.g. You should’ve listened to my advice. I was right all the time.
Shouldn’t (oughtn’t to) + the perfect infinitive is used to refer to an undesirable action in the past that did happen.
e.g. You shouldn’t have told him he was a loser. It was callous.
f)Need is a modal verb, with no 3rd person form. It is used mainly in questions and negatives. The meaning is similar to have to.
e.g. Need you ask? The Prime Minister need not worry.
Need tois a normal verb.
e.g. Sarah needs to be more careful. You don't need to worry. Do I need to fill in this form?
g) Didn't need todescribes a past situation, where something was not necessary, so it was not done.
e.g. Kate looked after the children, so we didn't need to take them to the nursery.
Needn't have donedescribes a past situation, where something happened or was done, but it was not necessary.
e.g. I needn't have gone so early to the office. The meeting was cancelled.
a) May, can and could are used to ask for permission.
e.g. May I use your phone?
Can/could I go home?
May is used to give permission, but it sounds very formal. Can and can’t are more common.
e.g. You can use a dictionary in this exam.
You can’t stay up till midnight.
To talk about permission generally, or permission in the past, we use can, could or be able to.
e.g. Children can (are allowed) to do what they want these days.
a) Can expresses ability. The past is expressed by could. Other forms are provided by be able to.
e.g. I can speak three languages.
I could swim when I was three.
I’ve never been able to understand her.
b) To express a fulfilled ability on one particular occasion in the past, could is not used. Instead we use was able to or managed to.
e.g. She was able to survive by clinging onto the wrecked boat.
The prisoner managed to escape by climbing onto the roof.
c) Could + the perfect infinitive is used to speak about an unrealized past ability. Someone was able to do something in the past, but didn’t try to.
8 A is bound to have let В must have let С can let
9A canВ may as wellС might
10A should have started В must have started С might have started
5. Complete the email with the words below. may be seeing may have left could be coming
may not have done couldn't have left may have found
could have fallen may be visiting
From: Robin Nicholas
To: Helena Shakespeare
Subject: Seeing you again
It was good to see you last week and to get your email yesterday.
Sorry to hear you lost your rap CD on the journey home. I've looked for it, but it definitely isn't in our car. I think you (1) it on the train. Why not phone the lost property office? It (2) down the side of your seat. Someone (3) it and handed it in. Of course, if they like rap music, they (4)! Anyway, as far as I remember, you (5) it here, because you were listening to it on the way to the station.
And now my news. Guess what? I (6) to your part of the world next month! There is a conference in your town which my boss wanted to attend, but now he's heard that some important clients (7) our office at that time.
So, we (8) each other sooner than we expected. Let's hope so. Of course it's not settled yet. I'll email as soon as I know for certain.
6. Complete the text using one of the phrases a-j in each gap.
a) can't have set off b) could easily be c) could expect d) must have been
e) can't have been f) could easily sail g) might have h) must have made
Imagine what it (1)like to have sailed around the world in a small wooden ship, as Drake and his men did in 1577-1580. On a ship only some 35 metres long, it (2) easy for the 80 or so crew to live comfortably. Exploration was part of war and rivalry with other nations, so these voyages (3) attacks on other ships and towns, and had to make a profit. There were all the usual dangers too. A ship (4) destroyed by a storm or run out of food and water, and the captain (5) little idea of where the ship was or where it was going. Explorers (6) many wrong decisions in an age when there were only basic maps and navigation equipment, and in unknown parts of ocean where a ship (7) for weeks without reaching land. Very often places they thought they (8) turned out to be much further on, or in a different direction. However, they (9) on such long voyages without some general idea of the places they (10) to reach along the way, and as knowledge of navigation improved, voyages became more and more successful.
7. Complete the answers with must, can't or might and any other words you need. 1. GERALD: Can that be James phoning at this hour? It's gone midnight!
HILDA: It…him. He said he'd phone if he passed his exam.
2. JIM: There's a light on in that office block. Do you think it's a thief?
HARRY: It…the cleaners. They always work at night.
3. ELINOR: Where did Adam get that new guitar? He hasn't got any money
KATE: It … a present. After all, it was his birthday last week.
4. NICKY: Why did Mina ignore me at the party last night?
RYAN: She …you. She wasn't wearing her glasses.
5. EMMA: Do you think Cindy told the boss I left work early yesterday?
NEIL: She's away this week, so she … him.
6. JILL: What's making me feel so ill?
PAT: It … ate. Did you have seafood last night? That sometimes makes people ill.
8. Re-word the following sentences using can, may or must.
I don't think he did it all by himself.
Perhaps, you're right.
It is possible that they forgot it in the car.
Is it really true?
I don't believe he has been meaning to do it.
It is impossible that he should have refused your request.
Evidently he has not read the book.
I'm certain that he has heard the gong.
It was some special occasion, I'm sure.
He looks wet and muddy. I'm sure he has been fishing.
No doubt, she is out shopping.
It's possible that he doesn't know we are here.
Is it possible that he is giving a course on the Renaissance at the University?
It is possible that the news is being broadcast on all the channels.
I'm certain they didn't take notes of the meeting.
Is it possible that we are out of wrapping paper?
It is possible he will again forget to rule a margin down the left side.
Then the firing began again. This time it was impossible for it to be more than a mile away.
Let's give her a call again. It is possible that she was asleep and didn't hear the telephone.
You have used up all the money I gave you, I suppose.
I'm sure she's at home.
I'm certain you're crazy.
I know that isn't Janet - she's in America.
I'm sure she thinks I'm stupid.
I bet I look silly in this coat.
They're always buying new cars - I'm certain they make a lot of money.
I'm sure he's not a teacher - he's too well dressed.
You're an architect? I'm sure that's an interesting job.
I'm sure you're not serious. I know you're joking.
I'm sure he's got another woman: he keeps coming home late.
9. Write a new sentence with the same meaning, beginning as shown. 1. Running is not allowed on the stairs. There is a danger of accidents.
Running is not allowed on the stairs. You .................................................
2. You'd better not use this ladder. Look at it! I'm sure it's not safe.
You'd better not use this ladder. Look at it! It
3. I think I know how this window got broken. I'm sure someone kicked a ball against it.
I think I know how this window got broken. Someone
5. I've turned off the electricity. I'm sure it's safe to touch these wires now.
I've turned off the electricity. It
6. Ouch! Why didn't you tell me that piece of metal was hot!
Ouch! You !
7. Where are the fire fighters? I expected them to have arrived by now.
Where are the fire fighters? They
8. I'm sure you didn't clean this bowl properly.
You I can see stains on it.
10. Read these three short texts about missing people. Then speculate about what you think happened in each case. Use must, might and can’t.
Linda Peyton has bee missing for three weeks. It is known that she was staying in a hostel near Exeter until quite recently and it is thought that she has a boyfriend in Bristol, over 50 miles away. Linda is only 16 years old and should have been attending school. Her family are worried about her and would like her to get in touch and let them know she’s OK. Linda had been living with her grandparents. According to her grandfather, Linda enjoys shopping, is very creative and had hoped to become a beautician.
Richard Withers, 43, went missing from his home in Eastbourne last October, leaving behind his glasses, credit cards and various personal documents. Richard was due to report to work at a local factory, but never turned up. His mother claims that he left the house that day ‘in a distressed condition’ because he had recently been beaten up in a street fight and had also been having some serious personal problems. Richard is a keen football supporter who often went to watch Brighton & Hove Albion play. His mother described him as ‘a lovely, helpful man who wouldn’t hurt a fly’.
Skip Hudson disappeared on Christmas Eve last year. That day, he was due to fly to Almeria in Spain with his fiancée and had gone to the bank in Cleethorpes to withdraw some money. He never came back and has not been seen since. Skip had apparently bee looking forward to the holiday, despite his fear of flying. He had never flown before. There was a reported sighting of him on Boxing Day in a nearby town. Skip used to work as a mechanic in a local garage and was also a keen fisherman.
II. Other uses of modal verbs. 1. Can, could, able to. Choose the correct alternative.
Why did you walk all the way from the station? You could рhone / could have phoned for a lift.
I loved staying with my grandparents when I was a child. They let me read all the books in the house and told me I could go / was able to go to bed as late as I wanted.
This carpet was priced at £500, but I could get / was able to get a discount because of this little mark in the corner.
I couldn't have found / haven't been able to find my diary for days. It's terribly inconvenient.
I've no idea where my brother is living now. He can be / could be at the North Pole for all I know.
It's difficult to understand how explorers survive the conditions they encounter in the Antarctic. I'm sure I can't / couldn't.
I wish I'd had your opportunities. With a proper education I can be / could have been a rich man now.
The day started off misty, but the sun had appeared by the time we reached the mountain and we could climb / were able to climb it quite quickly.
Our holiday flat had a kitchen. We could cook / could have cooked our own meals, but we preferred to go to local restaurants.
Why did I listen to you? I can be / could have been at home now instead of sitting here in the cold!
2. Use can, could or able to in the following sentences.
. . . you stand on your head? - I . . . when I was at school but I . . . now. (2nd verb negative)
When I've passed my driving test I . . . hire a car from our local garage.
At the end of the month the Post Office will send him an enormous telephone bill which he . . . pay. (negative)
I ... remember the address, (negative) — . . . you even remember the street? (negative)
When the fog lifts we . . . see where we are.
You've put too much in your rucksack; you never . . . carry all that.
When I was a child I . . . understand adults, and now that I am an adult I . . . understand children, (negative, negative)
When you have taken your degree you . . . put letters after your name?
Don't try to look at all the pictures in the gallery. Otherwise when you get home you . . . remember any of them, (negative)
When I first went to Spain I. . . read Spanish but I . . . speak it. (2nd verb negative)
. . . you type?- Yes, I . . . type but I ... do shorthand. (2nd verb negative)
I'm locked in. I . . . get out! (negative) - . . . you squeeze between the bars? (negative) -No! I . . .; I'm too fat. (negative)
... I speak to Mr Pitt, please?- I'm afraid he's out at the moment. . . . you ring back later?
If you stood on my shoulders . . . you reach the top of the wall? ~ No, I'm afraid I . . . (negative)
If I sang . . . you accompany me on the piano? -No, I. . ., I . . . play the piano! (negative, negative)
If a letter comes for me . . . you please forward it to this address?
She made the wall very high so that boys . . . climb over it. (negative)
They took his passport so that he . . . leave the country, (negative)
. . . you tell me the time, please? — I'm afraid I. ... I haven't got a watch, (negative)
If you had to, . . . you go without food for a week? — I suppose I ... if I had plenty of water.
. . . you lend me £5? -No, I . . . (negative)
They used to chain valuable books to library desks so that people . . . take them away, (negative)
He says that he saw Clementine drowning but. . . help her as he . . . swim, (negative, negative)
If you had had the right tools . . . you have repaired the engine?
3. Complete the sentences with could(n't) and was(n't) able to. Sometimes there is more than one answer.
Eddie broke his leg last summer, so he … swim.
Emily's handbag was stolen when she was out yesterday afternoon. Luckily she met a friend, so she … use his mobile to call home.
I didn't enjoy the play because I forgot my glasses. I … see the stage properly.
Marion's meeting was cancelled at the last moment, so she … come to the sports club with us after all.