Cleft Sentences

David ate the last piece of cake.
It was David who ate the last piece of cake.
Cleft Sentences = add emphasis to a noun, person, time phrase or clause

1) A thing: It is/was … that …
e.g. It was the candle that caused the fire.

2) A person: It is/was … who …
e.g. It was Martin who sang the best.

3) Reasons: It is/was because …
e.g. It is because of the strike that the lessons are cancelled.

4) Time: (only) when, while, not until + verb clause
e.g. It was only when I had to pay for the coffee that I realised that I had left my wallet at home.

It was while I was paying that the thief snatched my bag.

It is not until you do the test that you realise you need to study more.

What … is/was ….. (= frequent in conversation)

1) nouns, noun phrases, gerunds
e.g. What I can’t stand about the flat is the tiny kitchen.
What we liked most on holiday was not having to get up early.

2) Actions
e.g. what happened was (that) I missed my train and was late for the appointment.

3) embedded questions
e.g. what I’d like to know is how you can go out every night and not be tired the next day.

Stress the piece of information being emphasized.