Non-finite parts of a verb are those that do not indicate number, person or tense.
The common non-finite forms are:
- the base form
- the present participle or -ing form
- the past participle
- the to infinitive
There are also other non-finite forms, such as:
- the continuous to infinitive: to be teaching
- the perfect to infinitive: to have taught
- the passive to infinitive: to be taught
The base form
As well as serving as the verb form on which most of the other parts of the verb are based, the base form is frequently used as a non-finite part of the verb. Because of this it is sometimes called the ‘bare infinitive’ or the ‘infinitive without to’.
The base form is used as a non-finite part of the verb in these ways:
- after modal verbs.
- You must stop at the kerb before you cross.
- He should think before he speaks
After let’s (suggestion) and let (permission) and make (compulsion)
- Let’s invite Annette round for dinner.
- Let the cat go!
- Make him stop!
- Let him finish what he was saying!
after feel, hear, see, watch + an object.
- I heard him run downstairs.
- Later we saw them leave the house.
- after a to infinitive to which it is joined by and.
- I want you to sit and listen.
- Just wait and see.
after would rather and had better.
I would rather go out, but I think we had better stay home and finish the painting.
Verbs of perception may be followed either by the base form or by the -ing form. There is often a change of sentence meaning.
These verbs include: see, hear, feel, smell, listen to, watch
We watched her park the car = we watched the whole event.
We watched her parking the car = we may only have seen part of the event.
I heard a cuckoo call = I heard just one call.
We heard the birds singing = We heard part of the song of the birds.