10.26 'it' as the subject

If you want to emphasize one noun group and make the whole clause say something about it, you can make it the complement of an impersonal 'it' structure, and follow it with a relative clause containing the rest of your message. The complement can refer to the subject or object of the relative clause.

For example, instead of saying 'George found the right answer', you may want to stress the fact that George did it by saying 'It was George who found the right answer'.

Similarly, instead of saying 'Henry makes clocks', you can say 'It's clocks that Henry makes'.