Infinitive
From TEFL World Wiki
The infinitive is the base form of the verb:
be, have, walk...
Often the infinitive is introduced by the participle, to:
to be, to have, to walk...
Note, when the infinitve is on its own it's sometimes known as the bare infinitive; when it's with to then it's sometimes known as the full infinitive.
Bare Infinitive Usage
1. After most modals and auxiliary verbs
We should go now.
They must arrive soon.
Note that the main exception here is the modal ought to.
2. With some verbs of perception
{verb of perception} + {object} + {infinitive}
I watched it explode.
I heard them shout.
Full Infinitive Usage
1. As a noun phrase
To be or not to be.
To put it bluntly: you're wrong!
2. To express reason
{to} + {infinitive}
To pay for the mortgage, he took a second job.
A common question and answer expressing purpose is like this:
| statement: | I'm packing now. |
| question: | What for? |
| answer: | To save time later. |
Double Infinitive
Sometimes we need to use more than one infinitive in a row:
A picture can be useful to help to explain what happened.
Although correct grammatically, this can sometimes sound a little awkward and we can say instead:
A picture can be useful to help and explain what happened.
Alternatively, we can say:
A picture can be useful to help explain what happened.
These are all correct.
