Unit 3
Modal Verbs of Obligation

MUST

The modal verb must has only one form. We only use must to talk about the present and the future. For missing forms of the verb must we use its equivalent to have to.

Must expresses:

1 Strong obligation, necessity, duty to do something. We generally use must when the speaker has decided that something is necessary.

Must expresses an obligation from the speaker’s point of view, an obligation imposed by the speaker; it is used to give a strong personal opinion: The dogs believe they must keep it a secret.

As must expresses a strong obligation, we do not often use it in face-to-face conversation as it can sound impolite and often inappropriate. We often use should and ought to as an alternative to must as they express a subjective (often moral) obligation felt by the speaker, but the obligation is weaker than with must

You should treat your neighbours with more respect and never bark at their cats.

2. Prohibition; refusing permission

Must is used in negative sentences when it is forbidden/prohibited to do something; you are not allowed to do something; it is against the rules/laws:

The dogs were astonished when they saw: «You mustn’t go by train if you haven’t got a ticket (even if you are a dog).»

3. Command, urgent request, command in public notices or documents:

You must do as you are told.

In the present we can use both forms: must and have to.

Remember the difference in sentence formations: we use auxiliary do/does for to have to while making questions and negative sentences: Do the dogs have to buy train tickets? – No, they don’t have to do it.

Must is similar to have to but we use have to (not usually must) to say what someone is obliged to do: Luna has to let her parents know where she is. (She is obliged to do it, it’s not her intention)

Mustn’t and don’t have to are completely different:

You mustn’t do something = it is necessary that you do not do it (so don’t do it):

You don’t have to do something = you don’t need to do it (but you can if you want):

EXERCISE 1

Complete the sentences with must/mustn’t or have to/has to/don’t/doesn’t have to.

1 The dogs ***** get into the train again to find Kit.

2 They ***** worry. Kit is clever enough to find the way back home.

3 Anyway, the kitten ***** be left alone on the train.

4 Does everybody ***** return or does Luna alone ***** look for the pet?

5 The dogs have decided they ***** do everything together.

6 Whatever they do, they ***** separate.

7 They got into the train again and suddenly saw the poster: «If you have lost each other on the train, you ***** panic. Use our radio to make an announcement.»

TO HAVE TO

When we talk about past obligations or necessity, we use had to. The dogs had to come back.

Future obligation can be expressed by must or made more precise with will have to.

They will have to get back to the forest as soon as they find the kitten.

The form have to is also used for Perfect Tenses.

They have just had to get into the train again.

They had had to do it very quickly before the train left.

They will have had to return to the forest before dark.

Must has no infinitive, gerund or participle forms. So when necessary, we make this form with have to.

Chilly hates having to waste time.

He never used to have to take care of pets.

Having to look for Kit, the dogs might waste a lot of time.

EXERCISE 2

Complete the questions with the correct form of have to/must and answer them:

1 Is there anything you ***** do for your job or study which you hate?

2 When was the last time you ***** catch a train?

3 Name two things you ***** do every day.

4 What do you hate ***** do?

5 What did you use to ***** do when you were little?

6 What would you ***** do if you were shipwrecked?

7 What will you ***** do to save money for a rainy day?

EXERCISE 3

Complete the sentences using the proper verb and the correct form of must/have to: tell, bark, come back, run, get away, face, pinch, look for

1 The dogs ***** along all the aisles looking for the kitten but couldn’t find him anywhere.

2 Luna was extremely furious because of ***** Kit a dozen times that he ***** from her.

3 ***** the kitten in every corner of this long train, the friends were getting angrier and angrier, more and more exhausted.

4 They had already lost any hope to find the kitten on the train and thought of ***** to that platform when Chilly made a sudden stand.

5 He couldn’t believe his eyes and ***** himself to make sure it was not a hallucination.

6 There was somebody’s sweater on a berth and Kit enjoying such a balmy sleep on it that Chilly ***** loudly to wake him up.

7 When Kit realised what had happened, he got so embarrassed that was ready to do anything to avoid ***** Luna.

SHOULD AND OUGHT TO

Should and Ought to are very much alike in meaning and are often interchangeable. They are very common in spoken English. They have only one form; ought is always followed by the to-infinitive.

Should and Ought to express:

1. Mild obligation, moral or mild/weak duty, responsibility (in this meaning ought to is preferable).

should and ought to are less emphatic than must and have to:

with should the person has some choice on whether or not to act, but with must he has no choice.

Kit should apologise. (= it would be a good thing to do)

Kit must apologise. (= he has no alternative)

2. Advice, desirability, recommendation. (in this meaning should is more common).

We are talking about what is a good thing to do or the right thing to do: Luna thinks Kit should apologise to all the dogs.

3. Should (ought to) have + past participle can mean something that would have been a good idea, but that you didn’t do it. It’s like giving advice about the past when you say it to someone else, or regretting what you did or didn’t do when you’re talking about yourself.

Kit should have stayed with the dogs.

Shouldn’t (oughtn’t to) have + past participle means that something wasn’t a good idea, but you did it anyway.

He shouldn’t have run away.

EXERCISE 4

Chilly is keen on giving advice. Complete the sentences using the proper verb and the correct form of should/shouldn’t: move, use, take, catch, make, trust, yell,

1 You ***** dogs. They always know who to stay away from.

2 If you hear weird noises in the night, you simply ***** weirder noises to confirm your domination.

3 If you find a toilet in your dream, you ***** it.

4 You ***** at cats, lean in close and whisper, it’s much scarier.

5 If you are not happy where you are, you *****. You are not a tree.

6 If you drop a cactus, you ***** it.

7 You ***** decisions without eating first.

TO BE SUPPOSED TO

We can use be supposed to + infinitive instead of should/ought to to talk about an obligation to do something. It is commonly used in spoken English to express a less strong obligation which is frequently ignored: Kit is supposed to be with Luna all the time.

We can use be not supposed to’ to express prohibition:

He is not supposed to run away again.

TO BE TO

To be to is a modal expression, whose meanings are close to those of modal verbs and expressions denoting obligation: must, to have to, should, ought to.

to be to is used in the Present and Past Simple Tense.

To be to expresses:

1. Obligation or necessity arising out of an arrangement, an agreement or plan.

Luna is to come back home by midnight.

to be to in the Past Simple + Perfect Infinitive shows that the action had been arranged but did not happen. (was/were to have done)

Kit was to have stayed in Luna’s bag all the time.

to be to in the Past Simple + Simple Infinitive does not show whether the action was or was not carried out and, on the other hand, it is the only way to show a fulfilled action. (was/were to do)

Chilly was to arrange the trip.

2. Strict orders, formal commands or formal instructions.

3. A strict prohibition. May not, can’t, are not to, must not – are arranged in increasing order of severity, «must’ being an absolute prohibition: Kit is not to leave the bag until he is allowed to do it.

EXERCISE 5

Luna’s scolding Kit. Complete her sentences using the correct form of the verb in brackets with to be to and to be supposed to:

1 You ***** /obey/ me.

2 You ***** /stay/ in the bag as I had told you before the trip.

3 You ***** /let/ me know about all your intentions.

4 You ***** /tell/ me that you were going to leave the bag.

5 You ***** /have/ any secrets from me.

6 You ***** /share/ all your ideas with me instead of doing everything on your own

7 You ***** /be/ always with me so as not to make me worry big.

EXERCISE 6

Fill the gaps in the story with missing words:

Having ***** Kit, the dogs were able to resume looking ***** Kudjo. The friends had to hurry because it was getting ***** and they were supposed to come back home before nightfall. Feeling guilty and miserable, Kit kept ***** in Luna’s backpack. If he ***** run away, the dogs wouldn’t ***** wasted so much time. If the dogs hadn’t ***** so much time, they would have already ***** Kudjo. If they had found Kudjo, everybody would be ***** and cheerful. He must do something to ***** the situation. He ***** find Kudjo. If he does it, everybody will ***** him. But he can’t do it while sitting in the ***** and he isn’t allowed to get out of it. It’s totally out of the question. Suddenly it dawned on him that he ***** be able to get away in the backpack. Luna forbade him to leave her *****, but she didn’t forbid her bag to *****. What a smart kitten!

EXERCISE 7

Find and correct 7 mistakes in the sentences:

1 Luna should left Kit at home but she didn’t.

2 The dogs must to return so as to find the kitten.

3 Kit was supposed to stayed in the bag all the time.

4 Fortunately, the dogs hadn’t to come back home because they had found Kit.

5 Luna has just must to punish her pet.

6 Kit must not to do anything on his own!

7 He doesn’t have to disobey Luna anymore, otherwise, he’ll be punished.

EXERCISE 8

Choose the correct option:

1 Luna ***** at the kitten. He is too little, after all.

a shouldn’t shouted

b shouldn’t have shouted

c mustn’t have shouted

2 Chilly believes Kit *****.

a will be to be grounded

b was to have been grounded

c was to have grounded

3 Cuba thinks Kit ***** be so naughty and stubborn.

a shouldn’t

b needn’t

c oughtn’t

4 Kit doesn’t think the dogs *****to worry about him so much.

a ought

b should

c must

5 The kitten didn’t use ***** obey anybody before.

a to have

b to must

c to have to

6 Luna ***** admit not bringing up her pet at all.

a just must

b has just had to

c has just musted

7 She ***** him some basic rules of behaviour but she didn’t.

a had to teach

b must have taught

c should have taught

EXERCISE 9

Translate the story:

Кит должен был найти Куджо первым, чтобы доказать всем на что он способен. Он решил передвигаться, не вылезая из сумки. Он же обещал Луне оставаться в рюкзаке и он должен сдержать свое слово. Так как собаки горячо спорили в какую сторону идти, никто не заметил, как рюкзак тихонько откатился от них и пополз по тропинке в лес.

Он полз и представлял себе, как все удивятся и обрадуются, когда он вернется вместе с Куджо. Все наконец-то признают, что он не маленький беспомощный питомец, а полноправный член команды. Замечтавшись, котенок не заметил, как случайно свернул с тропинки и оказался в глухой чаще. Споткнувшись о поваленное дерево, Кит кубарем покатился на самое дно глубокой волчьей ямы. Очнувшись, он с ужасом понял, что самому ему оттуда не выбраться. Становилось темно и холодно. Было больно и очень-очень страшно.

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