"To have to"
As a modal verb "to have to" differs from the others that it is not defective. It can have the category of person and number and all tense-aspect forms. It is followed by a "to-infinitive". It builds up its interrogative and negative forms with the help of the auxiliary verb "to do".
HAVE notional (to possess)
auxiliary (in perfect tenses)
semi-auxiliary
to have + an infinitive a talk
(modal meaning) to have a walk
a bite
"To have + to-infinitive" is a modal construction which expresses circumstantial necessity.
to have to = to be obliged to
It is often rendered in Russian by means of "приходиться, вынужден" and shows that there is no other way out.
She is usually short of time so she has to go by car.
In the past tense "have to" indicates a fulfilled obligation.
We had to do it again (and we did it).
"Have to" replaces "must" where "must" can't be used - to express past necessity; to express a future obligation; to express absence of necessity.
"Have to" can be used only with the indefinite infinitive.
Have got to = have to, but it is more usual in the colloquial speech, especially in the negative and interrogative forms. It is used only in the Present Indefinite.
Have you got to get up early morning?
The negative and interrogative forms are formed without any auxiliary.
"To be to"
notional – I was in the garden.
to be auxiliary – He is playing. It was done.
semi-auxiliary (modal) –1 was to come at 5.
"To be to" as a modal verb is used in the Present and Past Indefinite tenses and expresses:
Prearranged necessity
Remember, that we are to meet at 5.
The metro station is to be built in this district.
When am I to come?
NOTE: When the verb "to be" in its past form is followed by a perfect infinitive it shows that a planned action didn't take place.
He was to have come yesterday (that means that he didn't come).
Commands, orders, instructions.
You are to leave me alone.
He is to stay here until I return.
In negative sentences it expresses strict prohibition.
You are not to do that.
You are not to smoke here.
When used in questions it expresses asking for instruction.
What am I to do further?
Where am I to go? (Куда же мне деваться?)
3. Something unavoidable in the future which corresponds to the Russian "суждено","предстоит".
She was to become his wife.
He is to be a musician.
He was never to see her again.
It was not to be.
Sometimes but only in combination with the passive infinitive it may express possibility.
Nothing was to be seen.
Nothing could be seen.
"NEED"
a full-meaning notional verb –1 don't need your help.
NEED
modal verb followed by an infinitive.
When "need" is used in the meaning of "to be in want of" it is treated as a normal verb.
He needs a new pair of shoes.
The modal verb "need" may be used either as a defective or as a regular verb.
"Need" is mostly used in negative and interrogative sentences.
"Need" as a defective verb has only one form, which is the Present Indefinite. In reported speech it remains unchanged. It is followed by the infinitive without "to".
"Need" in negative sentences expresses absence of necessity.
When reference is made to the present or future it is followed by the simple infinitive.
You needn't do it now.
You needn't be afraid of me.
The negation is not always combined with the verb, but may be expressed by other parts of the sentence.
I don't think we need tell him this.
I need hardly say that I agree with you.
In questions "need" is used when there is a strong element of negation or doubt or when the speaker expects a negative answer.
Need I go there? (hoping for the negative answer)
I wonder if I need go there. (statement of doubt)
The defective form of "need" forms its negative and interrogative constructions without any auxiliaries.
NOTE: Sometimes in the literary language it is used with the auxiliary "do" and followed by the infinitive with "to".
We need to be careful.
He didn’t need to be told twice.
In negative statements "need" followed by a perfect infinitive shows that the action was done though it was unnecessary.
You needn't have got up so early. (He надо было, зря...)
We needn't have waited for her. (Можно было и не ждать, а мы ждали).
NOTE: "didn't have + indefinite infinitive" shows that the action didn't take place because of some circumstances (He надо было, не пришлось)