Intermediate Grammar

Intermediate · Grammar Reference

Unit 5 — Modal Verbs I

have to · modals · should/ought to/must · permission · requests · offers

5.1 have to

Form: has/have + to + infinitive

	+	–	?
I/you/we/they	have to go to school.	don't have to go	Do they have to leave?
he/she/it	has to study hard.	doesn't have to wear uniform	Does she have to study?
Past	had to work last night.	didn't have to	Did you have to go?
Future	will have to study hard.
PP	She's never had to do any work.

Use

Expresses strong obligation: You have to work hard if you want to succeed.
Obligation based on a law or rule, or on the authority of another person: Children have to go to school until they are 16.
Have to doesn't necessarily express the opinion of the speaker: The doctor says I have to lose weight.

5.2 have got to

Have got to is common in British English, but more informal than have to. More common in spoken than written English.

We've got to get up early tomorrow.I'm in trouble! You've got to help me!

Have got to expresses an obligation now, or on a particular occasion.

I've got to leave for work now. Bye!

📌 Note

He usually starts work at 9.00, but tomorrow he's got to start at 8.00 — a specific occasion.
Teachers have to prepare lessons — a general repeated obligation.

5.3 Modal and related verbs

The modal verbs are:

cancouldmaymightwillwouldshallshouldmustought to

They are used before other verbs and add meanings such as certainty, possibility, obligation, ability, and permission.

Key properties

No -s in the third person singular: She can ski. He must be tired.
No do/does/don't/doesn't in questions or negatives: What should I do? Can I help you? You mustn't steal!
Followed by the bare infinitive (no to): You must go. I'll help you.
Exception: ought to is followed by to-infinitive.
No infinitives or -ing forms — other phrases used instead: I'd love to be able to ski.
Usually no past forms — use with Perfect infinitive: You should have told me!

5.4 Obligation: should, ought to, and must

Should and ought to express mild obligation, suggestions, or advice. They express what is, in the speaker's opinion, the right or best thing to do.

You're always asking me for money. I think you should spend less.You shouldn't sit so close to the television!You ought to be more careful with your money.

must

Must, like have to, expresses strong obligation. Must can express an obligation that involves the speaker's opinion. It is personal.

I must get my hair cut. You must visit your parents.

Must is also associated with a formal, written style.

have to and must

Have to and must are sometimes both possible.
There is sometimes a difference: Must usually expresses the feelings and wishes of the speaker.
Have to often expresses an obligation that comes from somewhere else.

5.5 Permission: can and be allowed to

The main use of can is to express ability: I can swim.

Can and be allowed to express permission. Can is more informal and usually spoken.

You can borrow my bike, but you can't have the car. I need it.You're allowed to get married when you're 16.

5.6 Making requests: can, could, will, and would

There are many ways of making requests in English.

Can I speak to you, please? Will you help me, please?Would you mind passing me the water? Do you mind if I open the window?

Could is a little more formal; can is a little more familiar.

Could I try on this jumper? Could you tell me the time?

To be very formal or polite, add possibly to a request with could.

Could I possibly use your phone to make an important call?

5.7 Making offers: will and shall

The contracted form of will is used to express an intention, decision, or offer.

Come over after work. I'll cook dinner.It's Jane's birthday today. I'll buy her some flowers.

Shall I … / Shall we … ? is used in questions with the first person, I and we. It expresses an offer, a suggestion, or a request for advice.

Shall I carry your bag for you? Shall we go out for a meal tonight? Where shall we go?