Cleft sentences | C1 Grammar

A cleft sentence divides a message into two parts so one element receives special focus. Compare the neutral The timing caused the problem with It was the timing that caused the problem. The second version sounds like a correction: perhaps the problem was blamed on the budget, but the speaker wants to identify timing as the cause.

Clefts are useful when a conversation has a clear question in the background. If someone asks Who proposed the compromise?, It was Lena who proposed it puts the answer in the spotlight. If they ask What did Lena propose?, What Lena proposed was a compromise makes a different part of the sentence prominent.

The it-cleft

The basic pattern is It + be + focused element + that/who + remaining clause:

It was Lena who proposed the compromise.
It was on Friday that we received the warning.
It is the lack of evidence that concerns the panel.

The tense of be follows the time you are talking about: It was the final chapter that changed my view; It is the missing date that concerns us. Use who for people, especially in careful writing, and that for things or for people in many informal contexts. A place, time, reason or manner can be focused too: It was in the archive that she found the letter; It was because the road was closed that we arrived late.

A useful way to check a cleft is to mentally put the highlighted phrase back into the second clause. It was the key that Omar lost corresponds to Omar lost the key. The sentence is grammatical because the focused phrase fills the missing object position.

What-clefts and all-clefts

A what-cleft places a clause first and introduces the main point at the end:

What we need is a realistic timetable.
What surprised me was how calmly she responded.
What the team did was postpone the vote.

This structure works especially well when the focus is a whole idea, action or explanation rather than one simple noun. After what the team did, both was postpone the vote and was to postpone the vote are possible.

All-clefts narrow the message to one thing: All I wanted was a clear answer. Related patterns use the thing/reason/person/place ...: The reason we left was that the venue had closed. Avoid combining two ways of introducing the reason in careful prose: The reason was that the venue had closed, not usually ~~The reason was because the venue had closed~~.

Clefts are not just longer sentences

A cleft earns its place when the focus matters. In a neutral report, We received the warning on Friday is simpler. If the timing answers a question or corrects a misunderstanding, It was on Friday that we received the warning is more purposeful. Clefts can also help organise information: a familiar topic comes first and the new point arrives near the end.

Be careful with punctuation and clause completeness. What we need is more time has no extra it; what we need is already the subject of the sentence. In an it-cleft, retain the grammar of the remaining clause: It was Maya who noticed the missing page, not ~~It was Maya which noticed~~ in formal prose.

What the cleft tells the reader

A cleft does more than put a noun in bold. It gives the sentence a question-and-answer shape. It was the timing that caused the problem presupposes that there was a problem and identifies its cause. What caused the problem was the timing first frames the unknown cause as the question and then supplies the answer.

That distinction helps you decide between the two common patterns:

“When did you hear?” — It was on Friday that I heard.
“What did you hear?” — What I heard was that the office had closed.
“Who changed the figures?” — It was Karim who changed them.

An it-cleft often focuses a particular noun or adverbial. A what-cleft can package a whole action, reaction or proposition: What annoyed the audience was the delay, What she did was call the editor, What matters is whether the evidence is reliable.

Not until: cleft or inversion?

The same idea can be shaped in two ways, with different grammar:

It was not until midnight that they left.
Not until midnight did they leave.

The first is an it-cleft and keeps normal order in the that clause. The second fronts a negative time phrase and uses subject–auxiliary inversion. Do not combine the patterns: ~~It was not until midnight did they leave~~.

Agreement and natural phrasing

A what-clause is grammatically singular, so What we need is a clear answer is the usual form. When the complement is plural, speakers also use plural agreement, especially when the focus is a set of items: What we need are two additional chairs. In formal editing, many writers prefer singular is or recast the sentence (We need two additional chairs). The simplest sentence is often the clearest if agreement draws attention away from the point.

Clefting can also sound unnatural when the focused element does not fit the remaining clause. Try putting the phrase back into an ordinary sentence. If the result is incomplete or changes the intended meaning, choose a different construction. And if the focus is already clear, keep the direct form: Lena proposed the compromise needs no cleft unless the identity of the proposer matters.