How do modal verbs work?

What is a modal verb?

A modal verb (also modal, modal auxiliaryverb, modal auxiliary) is a type of auxiliaryverb that is used to indicate modality – that is,likelihood, ability, permission, and obligation.

YOU MUSTN’T EAT HEREYOU MUSTN’T TO EAT HERE

The MODAL verbs you need to know in unit 3 are:

COULD, MANAGED TO, CAN, WILL BE ABLE TO

MAY/MIGHT/COULD, MUST, CAN’T

SHOULD, MUST, HAVE TO

ABILITY AND ACHIEVEMENT: COULD, MANAGED TO, CAN, WILL BE ABLE TO

Before the 19th century, doctors could operate, but without anaesthetic (general ability in the past)

Scientists managed to clone an animal in the 1990s (specific achievement in the past))

Surgeons can now transplant human faces (present ability)

In the future we will probably be able to transplant brains (future ability)

Complete the text with positive and negative forms of can, could, managed to and will be able to

Boy in a bubbleWhen Rob Thompson was born, he had a defective immune system. Doctors________ save his life, but for years, he ______

Only survive inside a sterile plastic bubble or room. He ______ go outside orplay with friends. Later, scientists _________ develop a new gene treatmentfor people like Rob. Thanks to this treatment, Rob _______now do most of the things that a normal

Child can do, although he _______live without special drugs. In the future, scientists _______help other children with gene therapy. One day people likeRob ____live normal lives.

POSSIBILITY AND CERTAINTY: may/might/could, must, can’t

Your doctor may (not) ask you to give up smoking (possibility)

That new medicine might (not) cure you (remote possibility))

It could be more effective for some skin problems (possibility)

The stings must be painful (certainty)

Zootherapy can’t be a fraud, I’m sure it works! (certainty)

It may rain tomorrow. I may ask you to drive me to work. It might snow, but I don’tthink it will. It could rain heavily, that’s all. It must be dangerous to drive in the snow.It can’t be true. No, I don’t think it will snow.

Choose the correct alternative

James isn’t at school today. He ____ be ill.

a) can’t b) may c) may not

Sarah’s brother had a car accident. She ___be worried.

a) must b) might c) can’t

The children aren’t eating their vegetables. They___like them.

a) can’t b) must c) might not

ADVICE AND OBLIGATION: should, must, have to

You should give up eating between meals (advice)

We must cut down on fatty foods (obligation)

You don’t have to go without fast food (absence of obligation)

You shouldn’t eat so many of them (advice)

You mustn’t stay in class during the break (prohibition)

You have to get out more (obligation)

Complete the sentences with the correct form of the verbs from the box

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

0. If you want to learn how to swim, you should take lessons

1. You _______smoke in restaurants and cafés now –it’s illegal.

2. I _______buy a train ticket before I forget.

3. During the holidays, I ________go to school.

4. You ______go to bed late on a school night.

5. ______ you_______ study tonight?

PAST MODALS: possibility and certainty

It may have been a virus (we think this possibly happened/didn’t happen)

It can’t have done you any good (we think this definitely didn’t happen)

That could have helped him a lot (we think this possibly happened/didn’t happen)

She must have exercised every day (we think this definitely happened)

The burger might not have made you sick (we think this possibly happened/didn’t

happen)

Choose the correct option:

- Sian can’t / must have been at school today because she didn’tcome to English or Biology.

- I suppose she could / can have been ill.

- Maybe. But her mum’s just had an operation so she can’t / might have been at the hospital.

- Well, I saw her mum in the car yesterday so she must / couldhave already come home.