The modal verb must
The modal verb must has only one form – must - with reference to the present or future. In combination with the perfect infinitive it refers to the past. In indirect speech the rules of sequence of tenses are not observed, must remains unchanged in all meanings. Must has no form of Subjunctive mood, the mood auxiliary verbs should and ought to replace it in the subjunctive mood. Must has the following meanings:
Obligation, duty, necessity (from the speaker’s point of view).
In this meaning must is found in affirmative and interrogative sentences and is followed only by the simple infinitive: You mustn’t talk to your daughter about her future. Must he do it himself?
Prohibition, command
This meaning is expressed in negative sentences and must is followed by the simple infinitive:
He must not leave his room for a while. You mustn’t play with matches.May I smoke here? – no , you mustn’t
……………………- no, you can’t
……………………- no, you don’t
…………………….- no, you needn’t.
You mustn’t walk on the grass.
Supposition strong probability (bordering on assurance)
In Russian this meaning is rendered by the modal words “должно быть”
In this meaning must is used only in affirmative sentences and is followed by any form of the infinitive depending on the time reference: He must be ill, he looks pale. The book is not on the shell. She must be reading it. He must have told his mother about it, because when we came she already knew everything.
In negative sentences the words evidently and probably are used: Evidently she didn’t know my address.
In this meaning must is not used with reference to the future. In this case we find modal words probably, evidently, likely: She will probably come tomorrow. He will evidently know all about ill. She is likely to come in two days
Sometimes must expresses something that cannot be avoided , something that is inevitable: All experience show that men must die.
Must is used in the following set phrases:
must needs expressing obligation: He must needs go there. Он непременно должен пойти туда.
I must be going = I must be off – it’s time for me to go (мне пора уходить)
I must tell you that……. I must say… The meaning of obligations is weakened.
You must come and see me some time. You must come and dine with us. You must come and stay with us for the weekend.
This is a common way of expressing invitation .
The meaning of obligation is also weakened here.
To have to
To have to as a modal verb is not a defective verb and can have all the tense-aspect forms as well as the verbals: He is an invalid and has to have a nurse. She knew what she had to do. I shall have to reconsider my position. Having to work alone, he wanted all his time for his research.
In interrogative and negative forms of the modal verb to have to are built by means of the auxiliary verb do: Why do I have to do everything alone ? Did he have to tell them about it ? You don’t have to explain anything.
The verb to have to has the following meanings:
obligation, necessity imposed by circumstances. In the negative form – absence of necessity .
It is rendered in Russian as приходится, вынужден … In this meaning to have to is found in all kinds of sentences –affirmative, interrogative, negative, and is combined only with the simple infinitive: He had to explain everything. Did he have to do it? He did not have to tell me that he already knew.- нет необходимости
prohibition.
He mustn’t go there-
In spoken English the same meaning of obligation and necessity is expressed by have got to.
Like the verb to have to, it is found in all kinds of sentences and is combined only with the simple infinitive: Has he got to go right now? He hasn’t got to go just yet.
This combination may also be found in the Past tense, though it is not very common: He had got to sell his car.
The set phrase with have to is “had better”: A few drops began to fall. We had better take shelter. They had better not play cards when the guest might come in at any moment.
to be to
To be to as a modal verb is used in the Present and Past tenses. It has the following meanings:
a previously arranged plan or obligation resulting from this arrangement.
We are to discuss it next time. Is he to arrive tomorrow? Who was to speak at the meeting?
This meaning of to be to is found in affirmative and interrogative sentences in the Present and Past tenses. To be to is followed only by the simple infinitive.
The past tense of the verb to be in combination with the perfect infinitive denotes an unfulfilled plan:
I promised to go to a club with her last Tuesday and I already forgot about it. We were to have played a duet together.
order or instruction, often official (frequently in reported speech): The woman says I am to leave you alone. All officers are to report to the colonel at once.
In this meaning to be to is found in affirmative and negative sentences and is followed by the simple infinitive.
Something that is destined to happen: He has to be my teacher and friend for many years to come. He did not know that he was never to see his native place again. “I am never again to sing” – said the actress.
This meaning occurs in affirmative and negative sentences and to be to is followed by the simple infinitive.
Possibility.
In this meaning to be to is equivalent to can or may. It is used in all kinds of sentences in the Present and Past tenses and is followed by the passive infinitive: Her father was often to be seen in the pub. Where is he to be found? There is nothing to be seen. Nothing was to be done under the circumstances.
Set phrases: What am I to do? – что мне делать ? как мне быть ? What is to become of me ? – что мо иной будет ? Where am I to go?-куда мне деваться?
To be to as the form of the Subjunctive mood (were to for all persons) is found in conditional clauses of complex sentences: If he were to come again, I should not receive him.