The verbals have tense and voice distinction

Split Infinitive
The can be separates from the infinitive by an adverb and then it is called “SPLIT INFINITIVE”. It is not used in colloqural English.
He was unable to long keep silence.
The use of “to” without the Infinitive if it is easily understood from the contents.
Would you join me? - I’d love to, but I’m busy.
The functions of Infinitive
The infinitive can be used as:

1. 
   The subject
   

To doubt is almost to insult.
Even to think of his failure was a torture for him.
In the subject is expressed by an Infinitive phrase, the sentence usually begins with an introductory “IT” .
There is great pleasure to relax after a hard and tiresome day at the office.

2. 
   A part of predicate
   
   1. 
      To be in the meaning of “состоять в том чтобы”.
      

Her only desires is to be sent to London.

2. 
   After modal verbs.
   

This work can be done later.

3. 
   A part of a compound nominal predicate
   

I am happy to hear this good news.
He is always ready to help me.
They were glad to have been invited to the inauguration ceremony.

3. 
   An object
   
   1. 
      Direct
      

I can’t tell you where to find the girl.
Mother promised to give money for her journey.
I know what to answer.

2. 
   Complex object
   

They heard her shut the door.
I want father to buy me a car.

4. 
   An adverbial modifier of…
   
   1. 
      Purpose
      

She came to London to learn business.
He spoke politely so as (so that) not to offend her.
Ann is going to the health center to be examined.
The old woman walked slowly so as (in order) mot to fall.
To become rich you must be clever and work hard.

2. 
   Result “to and enough” , “too” express negative idea “enough” expresses positive idea.
   

It is too cold to bathe today
She was clever enough not to ask questions.
He was too old to be sent to this dangerous expedition.

3. 
   Reason
   

It was already late to start the work and they gave up the idea of succeeding.

4. 
   Comparison (as, if, as thought)
   

She rose from her chair as if to say something.
He fumbled in his pocked as if to find something to give the child.

5. 
   An attribute
   

He had no intention to marry the girl.
Ann’s desire to become President of the company mknew no bounds.
Here is a book to be given to Ann as a present for her birthday.
Bob is always the first to answer the teacher’s questions.
Nina was the last to come to the party.