This structureThe way in which the parts of a sentence, clause or expression are arranged. E.g.: make somebody + infinitive in "The teacher made me rewrite the composition." can express arranged eventA general term expressing that somebody or something does something or that something happens. E.g.: An apple fell on Isaac’s head.s.

The concert was to begin at 6.

However, if the planned event did not happen, we use be to + perfectThe aspect expressing completion. E.g.: He’s finished university. infinitive:

You were to have tidied your room this morning.

When used in the past tenseA grammatical category that is marked by verb inflection. To express when an event or action happens in time or when a state exists, we use tenses., this structureThe way in which the parts of a sentence, clause or expression are arranged. E.g.: make somebody + infinitive in "The teacher made me rewrite the composition." refers to an actionA general term expressing that somebody or something does something in the past which was fixed to happen at a determined timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc., and which may or may not have happened.

The train was due to arrive in a few minutes.

You should have been on time. (but you were not)
We ought to have protected the environment. (but we did not)

These can also be considered as criticism or advice.

The past form of need to is needed to, while need as an auxiliaryA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") is used with perfectThe aspect expressing completion. E.g.: He’s finished university. infinitives only in negativeA declarative sentence indicating "no". E.g.: Tim has no friends. sentences to refer to past timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc.. Note the difference between didn't need to and needn't +perfect infinitive:

Had to expresses past obligation, both external and internal, so it can be considered the past form of both have to and must.

I had to sleep.
He had to correct his composition himself.

This structureThe way in which the parts of a sentence, clause or expression are arranged. E.g.: make somebody + infinitive in "The teacher made me rewrite the composition." can express actionA general term expressing that somebody or something does somethings that are fixed to happen at a determined timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc.:

You are due to hand in your home papers by the end of the month.

This structureThe way in which the parts of a sentence, clause or expression are arranged. E.g.: make somebody + infinitive in "The teacher made me rewrite the composition." can express arrangements and orders.

The concert is to begin at 6. (arrangement)
You are to tidy your room before your friends get here. (order)

Shall can be used with all persons in formalNot belonging to colloquial or everyday speech; official. E.g.: I demand that Mr Smith call the person on whom the committee has decided. rules and regulations:

"Thou shalt not kill." (archaic form!)
Members shall enter the names of their guests in the book provided.

You should be on time.
We ought to protect the environment.

In writing, should can also be used to express a strong obligation politely:

Guests should vacate their rooms by midday.