| Form | Example | |
|---|---|---|
| It-cleft | It + be + X + that/who + clause | It was John who called. |
| Wh-cleft | What/who/where + clause + be + X | What I need is sleep. |
| The thing/reason | The X that/why + clause + be + Y | The thing that worries me is... |
| Use | emphasis, contrast, correction | formal and emphatic structures |