8)Modal verbs of Obligation (Must, Be to, Have to, Have got to)

Modal verbs are used to show speaker’s attitude toward the action or state indicated by the infinitive, they show if this action is considered as possible, impossible, probable, obligatory, necessary, advisable etc.

M.v. are called defective because all of them (except dare and need) lack verbals and analytical forms. Besides, they do not take –s in the third person singular.

MUST

1) Smth is certain or highly probable (+) Mary must have a problem- she keeps crying. I cаn't find my keys; I must've left them at home. You must be joking!

2) Obligation that comes from the speaker; strong advice or order to oneself or the other person (+,?) You must be here at 8 tomorrow. (~Ты должен…, тебе необходимо. .) We mustn't go back on our word (~…не должны, нельзя...)

3) prohibition that comes from the speaker(-) - You mustn't open this parcel until Christmas Day

4) emphatic advice or invitation (+, -) You really must come and see us soon, (-Непременно...) You mustn't miss this chance (~Ни в коем случае не…)

5) emphatic, irritable reproach (?) - Why must you always leave the door open? Must you wear dirty old jeans the whole time?

6) smth regarded as inevitable owing to the laws of nature - Plants must have plenty of water and sunlight.

TO HAVE (GOT) TO

1) an obligation that comes from "outside" (circumstances, regulations, other people's orders) (+,?) Sorry I've got to go now. / 'm having to work very hard at the moment (temporary continued obligation)

Have got to is not normally used to speak about repeated obligations I usually have to start work at eight.

2) absence of necessity (-) Idon't have to cook my meals now that I'm married. Or: I don't need to cook.

TO BE TO

1) plans and arrangements (formal) The President is to visit Finland next month.

"To be + perfect infinitive" shows that a planned event didn't happen: He was to have moved out last week, but he changed his mind

2) “fate” Smth that is destined to happen - We were to meet again, many years later. (~... суждено...)

3) order - You are to do your homework before you watch TV.

4) prohibition – You are not to stay up so late.

9)Should & Ought to: their meanings, usage, combination with different forms of the infinitive.

The modal verbs ought to has only one form which is used with reference to the present or future. The modal verb should is used with reference to the present or future. In reported speech it re­mains unchanged.

Ought to expresses:

1. Moral duty, moral obligation (which is not always fulfilled). It corresponds to the Russian следует.

You ought to look after your children better (you don't always do it). Вам следует больше заботиться о детях.

When used with the perfect infinitive ought means that something right has not been done, a desirable action has not been carried out, and it, therefore, implies reproach.

You ought to have helped him (but you didn't). Вам следовало бы ему помочь. Не ought to have been more careful (he was not careful enough). Ему следовало бы быть более осторожным.

Ought not + perfect infinitive means that something wrong has been done and it is now too late to change it. It may also be viewed as a reproach. She told him he ought not to have done it (but he had done it).

2. Advisability (which is sometimes understood as desirability).

You ought to see a doctor. We really ought to buy a new car, oughtn't we?

3. Probability, something that can be naturally expected. It corresponds to the Russian должно быть, наверное.

You ought to be hungry by now (you probably are, but I'm not certain). Вы, наверное, уже проголодались. There oughtn't to be any difficulty (it's unlikely that there will be). Black Beauty is the horse that ought to win the race(... is likely to win ...).

In this sense ought is a weaker equivalent of must when the latter denotes near certainty

Ought to + infinitive is used when describing something exciting, funny or beautiful in the meaning of/ wish you could. You ought to hear the way he plays the piano!

Should

Should is nearly always interchangeable with ought to, as their meanings coincide. It expresses:

1. Moral obligation, moral duty, which may not be fulfilled. Should is found in this sense in all kinds of sentences. However ought to is preferable in this sense:

Не should phone his parents tonight, but he probably won't have time. Он должен позвонить, но, вероятно, у него не будет времени на это. If you see anything strange you should call the police.

Если ты увидишь что-то странное, ты должен вызвать полицию.

When used in the negative form should denotes a weakened prohibition, more like negative advice. He shouldn't be so impatient.

When combined with the perfect infinitive should denotes criticism, faultfinding; the statement indicates that something desirable has not been done. You should have put more sugar in the pie. It isn't sweet enough.

A negative statement indicates that something wrong has been done. They should never have married. They are so unhappy. Им вообще не следовало (не нужно было) жениться.

2. Advice, desirability. This meaning is more common with ought to than with should.

You should stay in bed. - Вам нужно (следует) лежать в постели. You should consult a doctor. - Показался бы ты врачу. (Тебе следует покачаться врачу.) As it is seen from the above examples, it is sometimes difficult to discriminate between the first and the second meaning.

3. Probability, something naturally expected (only with reference to the present or future).

The effect of the tax should be felt in high prices (will probably be felt). We needn’t get ready. The guests shouldn't come for another hour.

4. Request for instructions; offers and suggestions. When should I send this fax? Should I file these papers?

In most sentences should and ought to are interchangeable. However, should is more common in sentences expressing the opinion or suggestion of the speaker, while ought to is often used in recommendations connected with duties, regulations, laws.

You should wear sun-glasses. Your eyes are red. / Students ought to wear uniforms at this school.