Infinitive

We can use the Infinitive in several ways.

1.We can use the Infinitive as a Subject :

To abide by the law is behaving well.

To work hard is to succeed.

To learn is to become better.

To shave is necessary before going to office.

2.We can use the Infinitive as an Object of the Verb :

Human beings need to breathe.

We should cultivate a habit to think.

He wants to meet her.

They decided not to go.

3.We can use the Infinitive as a Complement to the Verb :

To understand is to become wiser.

To tell a lie is to fall in trouble.

To understand is to become wiser.

To understand is to become wiser.

To work hard is to progress in life.

4.We can use the Infinitive as Object to a Preposition :

The show is about to begin.

The train is about to arrive.

We have but to eat this.

The war is about to start.

5.We can use the Infinitive as Case in Apposition with It as Subject :

It is silly to speak like this.

It is good to do this work.

It is useful to work hard.

It is human to err.

It is harmful not to take exercise.

With some Verbs, to is not used with the Infinitive :   feel, hear, see, let, have, make, notice, watch, bid, dare, need etc.

For example :

Did you hear her call our names?

I can see him come inside.

Who needs speak like this?

I can feel the door vibrate.

We shall have him do this work.

Some Verbs necessarily take to with the Infinitive :    advise, allow, ask, begged, cause, command, compel, enable, expect, get, imagine, induce, instruct, like, order, permit, persuade, require, tell, want, wish etc.

For example :

The teacher allowed him to go.

The doctor advised him to take rest for two days.

The little girl wanted to have an ice-cream.

The commander commanded the soldier to run fast.

The use of to is optional with know and help :

Help him (to) finish this work on time.

I have known it (to) rain in winter here.

The Infinitive can be used to join sentences; for example :

*Komal went to market. She bought sugar.

Komal went to market to buy sugar.

*Shubham went to library. He borrowed a book.

Shubham went to library to borrow a book.

*There is some food in the fridge. I must eat it.

There is some food in the fridge to eat.

The Infinitive can be used to replace 'so that' in a sentence; for example :

*She was so afraid that she could not cross the road.

She was too afraid to cross the road.

*I am so glad that I cannot express it.

I am too glad to express it.