Angolban mikor használjuk a létigés mondatszerkesztést?

be + infinitive

A The be + infinitive construction, e.g. I am to go, is extremely important and can be used in the following ways:

1 To convey orders or instructions:

No one is to leave this building without the permission of the police.

(no one must leave)

He is to stay here till we return, (he must stay)

This is a rather impersonal way of giving instructions and is chiefly used with the third person. When used with you it often implies that the speaker is passing on instructions issued by someone else. The difference between (a) Stay here, Tom and (b) You are to stay here, Tom is that in (a) the speaker himself is ordering Tom to stay, while in (b) he may be merely conveying to Tom the wishes of another person.

This distinction disappears of course in indirect speech, and the be + infinitive construction is an extremely useful way of expressing indirect commands, particularly when the introductory verb is in the present tense:

He says, 'Wait till I come.' = He says that we are to wait till he comes. or when there is a clause in front of the imperative:

He said, 'If I fall asleep at the wheel wake me up.' = He said that if he fell asleep at the wheel she was to wake him up. It is also used in reporting requests for instructions: 'Where shall I put it, sir?' he asked = He asked where he was to put it.

2 To convey a plan:

She is to be married next month.

The expedition is to start in a week's time. This construction is very much used in newspapers:

The Prime Minister is to make a statement tomorrow. In headlines the verb be is often omitted to save space:

Prime Minister to make statement tomorrow. Past forms:

He was to go. (present infinitive)

He was to have gone, (perfect infinitive)

The first of these doesn't tell us whether the plan was carried out or not. The second is used for an unfulfilled plan, i.e. one which was not carried out:

The Lord Mayor was to have laid the foundation stone but he was taken ill last night so the Lady Mayoress is doing it instead.

B was/were + infinitive can express an idea of destiny:

He received a blow on the head. It didn 't worry him at the time but it

was to be very troublesome later, (turned out to be/proved

troublesome)

They said goodbye, little knowing that they were never to meet again

(were destined never to meet)

C be about + infinitive expresses the immediate future:

They are about to start. (They are just going to start/They are on

the point of starting.) just can be added to make the future even more immediate:

They are just about to leave. Similarly in the past:

He was just about to dive when he saw the shark. be on the point of + gerund has the same meaning as be about + infinitive, but is a shade more immediate.

be as an ordinary verb

Form: as for be used as an auxiliary