It as a preparatory subject
An infinitive can be used as the subject of a clause; however, this is not very common. When the subject of a clause is an infinitive expression, we usually prefer to start the sentence with an it.
- To talk to you is nice.
Although this sentence is grammatically correct, it doesn’t sound very natural. We can make it sound more natural by beginning the sentence with it.
- It is nice to talk to you.
More examples are given below.
- It is my ambition to become a superstar. (More natural than ‘To become a superstar is my ambition’.)
It can also be used as a preparatory subject for the for + infinitive structure.
- It is essential for the party to be a success.
Preparatory it is also used when the subject of the clause itself is another clause. A noun clause, for example, can be the subject of a clause. However, this doesn’t sound very natural.
- It seems probable that she will lose the battle. (More natural than ‘That she will lose the battle seems probable.’)
- It is essential that she should behave. (More natural than ‘That she should behave is essential.’)
It takes …. + infinitive
This structure is used to talk about the time necessary for things to happen.
- It takes me only five minutes to get dressed.
- How long does it take to get to Manchester from here?
It can also be used to emphasize one part of a sentence.
- It was John who broke the window. (Emphasis on the word John)
- It was the window that John broke. (Emphasis on the word window)