Bare infinitive (do)

Reasons for bare infinitive use

The bare infinitive is where the to of the full infinitive (to do) is not used. We use the bare infinitive because the words that come before it require this form or because of what the infinitive does in the sentence.

Bare infinitive after some verbs

There are only a few verbs in English after which we use this form of the infinitive.

Examples: make, help (full and bare infinitive possible with help with no change in meaning), let, hear, see, watch, and feel.

The teacher made me finish the exercise before I went home.

I helped the elderly man (to) cross the road.

My husband doesn't let me do any housework at all.

I heard an owl call in the woods behind our house last night. (It called once.)

I didn't see you leave this morning.

I watched her get up and leave the bus.

I felt someone touch me on the shoulder.

Notice that with the verbs of perception: hear, see, watch and feel, the following verb can be in the 'ing' form if there is a meaning of continuity of the action.

I heard an owl calling in the woods behind our house last night. (It called many times.)

We watched the lambs playing as we walked across the field.

With modal auxiliaries

We use the bare infinitive with modal auxiliaries: can, could, may, might, shall, should, will, would, must and need.

Can you help me carry this heavy bag?

You might have problems when you cross the border.

Shall I get you an aspirin?

We shouldn't get involved with things we don't understand.

Ought to is often considered a modal auxiliary, but in this case, the to is always used with an infinitive. In spoken English, to is usually used even when the infinitive is absent.

I ought to visit my grandmother more often.

You ought not to encourage him.

'You ought to visit your mother.' 'Yes, you're right. I ought to.'

Need can be a verb or an modal auxiliary. When need is a modal auxiliary, it takes the bare infinitive. This is more common in questions and negative sentences. Using need as a modal auxiliary may sound more formal than the verb form of need.

Need I attend the reunion? (modal)
Do I need to attend the reunion? (verb)

You needn't sign until full payment had been made. (modal)
You don't need to sign until full payment had been made. (verb)

With certain expressions

With some expressions we use this type of infinitive without to. Examples: had better, would rather, sooner (than), rather (than) and why.

You'd better do as she says. She's the boss.

I'd rather come next weekend - this weekend I'm busy.
(I'd rather come next weekend than next weekend.)

I'd sooner do it now than later.

Why wait when you could do it right now?
Why not get a new one?

More help on infinitives...

The full infinitive...

Infinitive with ing (gerund)...