The word ‘cleave’ (past tense: cleft) means: partially divided or split.
Before we start talking about cleft sentences, look at these two:
Sammy ate the pizza.
It was Sammy who ate the pizza.
Which of these two is emphasized? The first one, or the second one?
What is a cleft sentence?
The word “cleft” means partially divided or split. Cleft sentences are “divided” into two parts to emphasize something.
We use a cleft sentence to add new or important information to what the listener already knows. They are especially useful in written form because, in writing, we can’t show stress with our voices.
Think about the (pizza sentences) example again.
Suppose you were late to a pizza party. Your friend said she would save you two pieces. But by the time you arrived, all the pizza was gone. You think you know who ate your slices.
Listen to a short exchange:
Claudia ate the pizza, didn’t she? She loves pizza.
No. It was Sammy who ate the pizza. He came late, too, and didn’t know I was saving it for you.
In this example, your friend uses a cleft sentence to emphasize that Sammy ate your pizza, not Claudia.
Look at the following sentence:
The girls won the top science prize yesterday.
A few things can be emphasized in this sentence. Here are three possible it-clefts:
It was the girls who won the top science prize yesterday.
Here, the speaker is noting that the girls, not the boys or some other group, won the top prize.
It was yesterday when the girls won the top science prize.
Here, the speaker is noting that their win happened yesterday, not some other day.
It was the top science prize that the girls won yesterday.
And here, the speaker is noting that the girls won the top science prize, not second, third or last prize.
A tale of two clauses
It-cleft sentences are usually made of two clauses. You may remember that a clause is a part of a sentence that has its own subject and verb.
Some clauses can be complete sentences on their own. They are independent clauses. Some cannot be complete sentences. They are dependent clauses.
It was Sammy (independent clause) who ate the pizza (dependent clause).