Infinitive¶

Functions of the Zero Infinitive¶

The zero infinitive after verbs of perception.¶

With verbs of perception, the pattern is verb + object + zero infinitive:

He saw her fall from the cliff.
We heard them close the door.
They saw us walk toward the lake.
She felt the spider crawl up her leg.

The zero infinitive after the verbs make and let¶

Also see Causative

Her parents let her stay out late.
Let’s go to the cinema tonight.
You made me come with you.
Don’t make me study that boring grammar book!

The zero infinitive with why¶

The question word why is followed by the zero infinitive when making suggestions:

Why wait until tomorrow?
Why not ask him now?
Why leave before the end of the game?
Why walk when we can go in the car?
Why not buy a new bed?

Functions of Infinitive¶

Attribute¶

The Active Voice:

The scientists to solve this problem work at our institute.
He was the first to solve the problem.

The Passive Voice:

The problem to be solved is very interesting.
It was the first problem to be solved.

For complex¶

The Active Voice:

New conditions are needed for him to solve the problem.
For a wire to be a good conductor, it has to be made of low resistance metal.
For him to realize this dependence is rather difficult.
The tendency was for the substance to become ionised.
He wanted for me to check the result.

The Passive Voice:

For the problem to be solved you must join forces.

Other¶

The phenomenon to be considered later was discovered in 1923.
These questions will be discussed at the conference shortly to open in Moscow.
Newton was the first to discover the law of gravitation.

Complex Object¶

I would like the results to be given in a tabular form.
He proved his theory to be correct.
We take this value to be zero.
This apparatus enables accurate measurements to be made.

Complex Subject¶

This scientist is known to have developed a new theory.
His theory proved to be correct.
There seems to be nobody there.
There appears to be an excess of particles.
Exact data are unlikely to have been obtained.
An effect known to be due to the space charge is found by Meyer.
Substances, thought to possess this property are properly investigated.

“Tenses” of infinitive — [1]¶

Simple Infinitive — [1], [2].¶

Active Voice:

She plans to invite them.
Mike is afraid to make mistakes.

Passive Voice.

It is particularly common after auxiliary verbs (may, should, could, etc.) to indicate what is possible or what is correct. The passive infinitive is formed: to be + past participle.

They expect to be invited.
I am expecting to be given a pay-rise next month.
She is hoping to be elected president.
The carpet needs to be washed.
These doors should be shut at night.
This window may be opened but that one must stay closed.

Continuous infinitive — [1].¶

The continuous infinitive is used to express a continuing action after a verb or auxiliary which must be followed by the infinitive. The continuous infinitive is formed: to be + present participle.

As with the present infinitive, there are situations where the zero form of the continuous infinitive is required, so the word to is omitted. This happens after most modal auxiliaries, and in other places where zero infinitives are used:

I’d really like to be swimming in a nice cool pool right now.
I happened to be waiting for the bus when the accident happened.
It must be nice to be going to a wedding overseas.
You must be joking!
We should be hurrying. We’re late! (See Modal Verbs below)
You’d better be working on your report when I get there.

Perfect Infinitive — [1], [2].¶

Active Voice.

The perfect infinitive is most commonly found in type 3 conditional sentences as part of the conditional perfect, although it can be used in other places as well. The perfect infinitive is formed: to have + past participle. As with the present infinitive, there are situations where the zero form of the perfect infinitive is required:

He pretended to have seen the film.
Before I turn 40, I want to have written a book.
I would like to have been to the Taj Mahal when I was in India.
If I had known you were coming I would have baked a cake. (See Modal Verbs below)
Someone must have broken the window and climbed in. (See Modal Verbs below)
That man may have noticed the bank robbers’ getaway car. (See Modal Verbs below)

Passive Voice.

I am happy to have been invited.
I was on honour to have been chosen for the award.

Perfect continuous infinitive — [1].¶

The perfect continuous infinitive is used to express a continuing but now completed action after a verb which must be followed by the infinitive. The perfect infinitive is formed: to have been + present participle. As with the present infinitive, there are situations where the zero form of the perfect continuous infinitive is required:

The woman seemed to have been crying.
He pretended to have been painting all day.
I would have preferred to have been sleeping all afternoon.
You must have been waiting for hours! (See Modal Verbs below)
They might have been talking before you came in. (See Modal Verbs below)
You should have been studying for your test. (See Modal Verbs below)