To have (got) to

as a modal verb can have all the necessary tense forms. It is combined only with the Non-Perfect (Indefinite) Infinitive with the particle “to”.

The modal verb “to have to” expresses:

1. OBLIGATION OR NECESSITY ARISING OUT OF CIRCUMSTANCES

Synonym: to be obliged.

He has to go right now.

She knew what she had to do.

I shall have to reconsider my position.

Did he have to tell them about it?

Why do I have to do everything?

2. ABSENCE OF NECESSITY (in negative sentences)

(don’t (doesn’t) have to…, didn’t have to…, haven’t (hasn’t) got to…) = needn’t

You don’t have to stay with me, if it bothers you.

She knew what she didn’t have to do.

Note: the interrogative and negative forms of the modal verb “to have to” are built up by means of the auxiliary verb “to do”.

Have to replaces must where must cannot be used:

1. to express past necessity or obligation:

They had to do what they were told.

2. to express absence of necessity (in the sense of “needn’t”), because “must not” means prohibition:

You don’t have to make another copy of the document; this copy will be quite satisfactory.

3. to express future obligation (in the case the obligation is more precise):

You will have to take a taxi if you mean to catch the train.

MUST

has only one form for the present tense. It may also be used in reported speech. (the rules of the sequence of tenses are not observed with “must”)

1. Must followed by the Indefinite Infinitive may express:

1. OBLIGATION, NECESSITY, DUTY. (from the speaker’s point of view or with no freedom of choice)

Synonyms: to be obliged to; it’s necessary for somebody to do something (absence of necessity is expressed by other verbs (have, need)).

You must talk to him about this incident.

Must you really go so soon?

I decided I must stop smoking.

2. PROHIBITION (in negative sentences)

Synonym: to be forbidden

Students mustn’t stay away from classes without a good reason.

Cars must not be parked in front of the entrance.

3. EMPHATIC ADVICE, REQUEST, INVITATION (in affirmative and negative sentences)

You must come and see me sometime.

You mustn’t miss the film. It’s worth while seeing it.

You must stop worrying about your son. You mustn’t give another thought to what he said.

Note: “Must” may express emphasis. In this case “must” is not translated; it merely emphasizes some action or idea.

Of course after I gave her my advice she must go and do the opposites. (Ну, авжеж, після того, як я їй порадила вона раптом піди та й зроби навпаки.)

As we were starting what must he do but cut his finger. (Ми вже виходили, коли він раптом порізав собі палець (...візьми та й поріж...).)

At the time when everybody is in bed he must turn on the radio. (Саме тоді, коли вже всі сплять, він раптом вмикає радіо.)

2. Must combined with any form of the infinitive expresses:

1. STRONG PROBABILITY, SUPPOSITION IMPLYING ASSURANCE, NEAR CERTAINTY. (in affirmative sentences)

Synonyms: probably, evidently, surely, no doubt, undoubtedly, it’s clear that, in all probability.

He must be ill. He looks so pale.

The book is not on the shelf. Jane must be reading it.

He is smoking over there. He must have finished his work.

It must have been raining all the night. There are big puddles in the garden.

Note: When “must” expresses strong probability, it is not used:

1. with reference to the future. (in this case we find words “probably, evidently,(un)likely” in the sentence)

He will probably come tomorrow.

She will evidently feel lonely.

They are (un)likely to come.

2. in negative and interrogative forms. (the negative meaning is expressed by negative affixes, negative pronouns, or lexically)

Evidently (probably) they didn’t come to any agreement.

They must have failed to come to any agreement.

They must have misunderstood us.

He must never have guessed the truth.

He must be unaware of that.

They must have been inattentive.

They must have had no chance to warn you.

The letter must have been left unanswered.

TO BE TO

as a modal work is used in the Present and Past tenses. It expresses:

1. OBLIGATION arising out of (resulting from) the arrangement or plan (in affirmative and interrogative sentences)

Synonyms: to plan; to make a plan; to arrange; to agree; to decide.

We are to complete this work by tomorrow.

When am I to come?

I was to meet Mother at the dentist’s at 11.

Note: The past tense of the verb “to be” in combination with the Perfect Indefinite denotes an action that did not take place.

I promised to go to the club with her, and I really forgot all about it.

We were to have played a duet together.