The Grammaring Guide to English Grammar with Exercises

Modals to express necessity / obligation: MUST, HAVE (GOT) TO, NEED, SHOULD, OUGHT TO, SHALL

Modals to express obligation: MUST, HAVE (GOT) TO

The semi-modal NEED

Modals to express obligation: SHOULD, OUGHT TO

The modal SHALL to express obligation

Modals to express obligation: MUST, HAVE (GOT) TO

Present and future

Must refers to obligations which come from the speaker and may be directed at the speaker or the listener:

I really

must give up

smoking.

(directed at the speaker)

You

must keep

this secret.

(directed at the listener)

Have to expresses external obligations, which come from outside of the speaker. These may be rules and regulations imposed by an external authority:

I

have to get

to work by 9 every day.

Do

you

have to wear

a uniform at your school?

Absence of obligation is expressed with the negative form of have to, not with mustn't. Mustn't is used to express that it is necessary not to do something:

I

don't have to get up

early tomorrow. It's a holiday.

(I can get up late.)

You

mustn't tell

anyone. It's a secret.

(Don't tell anyone.)

Have got to has the same meaning as have to, but it is more common in informal, spoken language. The affirmative, negative and interrogative forms of have to and have got to are:

have to

have got to

I/you/we/they

have to

go.

I/you/we/they

have got to

go.

I/you/we/they

don't have to

go.

I/you/we/they

haven't got to

go.

Do

I/you/we/they

have to

go?

Have

I/you/we/they

got to

go?

He

has to

go.

He

has got to

go.

He

doesn't have to

go.

He

hasn't got to

go.

Does

he

have to

go?

Has

he

got to

go?

Must and will have to can be used to refer to future obligations:

You

must be

home by 10 o'clock.

I'

ll have to pay

my bills next week.

Past

Must has no past form. Instead, we use had to to express past obligations:

When I was at primary school, I

had to wear

a uniform.

We

had to start

all over again.

Quotes:

Life is like riding a bicycle - in order to keep your balance, you must keep moving. - Albert Einstein

A journey of a thousand miles must begin with a single step. - Lao Tse

If you tell the truth, you don't have to remember anything. - Mark Twain

Wise men speak because they have something to say; fools because they have to say something. - Plato

Some things have to be believed to be seen. - Ralph Hodgson

You must learn from the mistakes of others. You can't possibly live long enough to make them all yourself. - Samuel Levenson

To be successful, you have to have your heart in your business, and your business in your heart. - Thomas Watson, Sr.

Life is a shipwreck but we must not forget to sing in the lifeboats. - Voltaire

A man must be master of his hours and days, not their servant. - William Frederick Book

The semi-modal NEED

Present and future

Need can behave either as a modal verb or as a main verb:

As a modal verb, need is most typically used in negative sentences or in affirmative sentences with a negative meaning. It expresses absence of obligation or necessity, and it is followed by a bare infinitive: You needn't worry about that.

No one need be surprised at what happened.

You need only just ask.

I doubt whether I need help you.

Need as a modal verb also occurs in interrogative sentences, but this use is much more formal: Need you make so much noise?

Need as a main verb is followed by a to-infinitive and expresses that something is necessary. It can be used in affirmative, negative and interrogative sentences: Do you have a minute? I need to talk to you about something.

I don't need to be told that I should lose weight.

Do you need to use the hairdryer?

If you want good results, you will need to work harder.

Past

The past tense of the main verb need to is needed to: I needed to have my hair cut.

Why did they need to change the lock?

The negative form didn't need + to-infinitive normally refers to actions which were unnecessary and were not performed:We didn't need to buy any milk. We had plenty at home. (we didn't have to buy any milk, and we didn't buy any)

Need as a modal does not have a past tense form. Needn't + perfect bare infinitive (have + past participle), however, is used for actions which were performed but were unnecessary: We needn't have bought any milk. We still have plenty at home. (we bought some milk, but it wasn't necessary)

Quotes:

Gossip needn't be false to be evil - there's a lot of truth that shouldn't be passed around. - Frank A. Clark

Related topics:

The semi-modal DARE

Modals to express obligation: SHOULD, OUGHT TO

Present and future

Should and ought to + infinitive express obligation and duty. Should is used when we offer a subjective opinion, while ought to has a more general and more objective meaning:

I think you

should leave

.

We

ought to protect

the environment.

Past

Should and ought to + perfect infinitive express that an action which was desirable was not performed:

You

should have consulted

a doctor.

You

ought to have told

me earlier. Why didn't you tell me?

Quotes:

Gossip needn't be false to be evil - there's a lot of truth that shouldn't be passed around. - Frank A. Clark

We should read to give our souls a chance to luxuriate. - Henry Miller

Every English poet should master the rules of grammar before he attempts to bend or break them. - Robert Graves

The modal SHALL to express obligation

Shall is used to express formal rules and regulations or commands in an archaic style:

Visitors

shall be

accompanied at all times by a security guard.

You

shall not kill

.