1) with modal verbs and modal expressions e.g. I can tell you everything.
2) with verbs denoting various stages of actions - its duration, beginning or end e.g. I begin to understand you.
They gradually ceased to talk. They continued to whisper.
b) part of a compound nominal predicate (predicative) e.g. My intention was to see her as soon as possible.
Ill As Object
a) as the only object of the verb with such verbs as to agree, to arrange, to decide, to manage, to fear, to forget, to refuse, to promise, to fail, to plan, to hope, to seem, to pretend etc.
E.g. She agreed to come at 10.
b) as one of the two objects of the verb (with the verbs of inducement) - to advise, to leave, to make, to order, to let, to want, to ask, to expect, to help, to tell, to order, to warn, to invite etc. E.g. Tell him to hurry.
c) as the object with certain adjectives or participles: glad, pleased, anxious etc. E.g. I am glad to see you here.
d) with certain statives denoting psychological states such as afraid, agog, ashamed E.g. I am afraid to step inside the house.
IV. As Attribute
a) with nouns
E.g. The best thing to do is to go back.
b) with pronouns in -body, -thing, -one E.g. Have you anything to offer me?
c) ordinal numeral and adjectives last and next E.g. Jack was the first to come.
She was the last to reach the hall.
d) after quantitative adjectives much, little, more, less, enough E.g. I have no more to add.
e) the noun substitute one
E.g. I am not the one to discuss it.
V. Asan Adverbial Modifier
a) of result (after adjectives modified by too and enough) E.g. You are too young to understand it.
You are old enough to understand it.
b) of purpose
E.g. I have come to speak to you.
c) of comparison and manner (as if, as though] E.g. She moved her hand as if to stop him.
d) of attendant circumstances (ñîïóòñòâóþùèå îáñòîÿòåëüñòâà)
E.g. She opened the door to see the cat.
E.g. To tell the truth I would rather stay indoors.
b) verbs of mental activity (to know, to think, to suppose, to expect etc): E.g. He is supposed to be leaving tonight.
c) verbs of saying (to announce, to declare etc): E.g. He is said to have returned at last.
d) the verb to make:
E.g. He was made to keep silent.
VII. Infinitive clauseas subject, object or complement of sentence
a)Infinitive clause as subject
In older English, an infinitive clause could easily be the subject of a sentence.
E.g.To make mistakesis easy.
In modern English, this is unusual in an informal style. We more often use it as a “preparatory subject” and put the infinitive clause later.
E.g.It's easy to makemistakes.
b)An infinitive clause can be used after be as a subject complement.
E.g.My ambition was to retire at thirty.
Sentences like these can also be constructed with “preparatory it”.
E.g.It was my ambition to retire at thirty.
c)Infinitive as object
Many verbs can be followed by an infinitive clause in the place of the direct object. Compare:
E.g. I like cornflakesfor breakfast, (noun object)
I like to have cornflakesfor breakfast, (infinitive clause as object)
d)Infinitive with its own subject
Sometimes it is necessary to make it clear who or what is the subject ofan infinitive, especially if this is not the same as the subject of the sentence.
The subject of the infinitive is normally introduced by for.
E.g. For Ann to goto France would make me very happy.
(NOT Ann to go to France would...)
e)Infinitive clauses of purpose
We often use an infinitive to talk about a person's purpose - why he or she does something.
E.g. I sat down to rest,(NOTI sat down for resting/for to rest.)
We can also use in order to (more formal) or so as to.
E.g. He got up early in order to have timeto pack.
I moved to a new flat so as tobe near my work.
In order to and so as to are normal before “stative” verbs like be, know andhave.
E.g. I watched him in order to knowmore about him.
We normally use in orde/so as before a negative infinitive.
E.g. I'm going to leave now, so as not tobe late.
(NOT I'm going to leave now, not tobe late.)
f)Infinitive clauses: other uses
1. I came home to find...
Infinitive clauses can be used to say what somebody found out or learnt at the end of a journey or task.
E.g. I arrived home to findthat the house had been burgled.
The idea of surprise or disappointment can be emphasised by using only before the infinitive.
E.g. After driving all night we got to Amy's place, only to discoverthat she was away.
g) to hear her talk, you'd think...
The infinitives of see and hear can be used to explain the reason for a false impression. The infinitive structure is usually followed by you'd think or a similar expression.
E.g. To see them together, you'd thinkthey were an old married couple. But they only met yesterday.