It was ... that ... (clefts for emphasis) (B2 Grammar)

To put the spotlight on one part of a sentence, wrap it in It is / was + the part + that (or who for a person). The spotlighted part sits in the middle.

It was ... that ...

• John broke the window. → It was John who broke the window.
• I saw her yesterday. → It was yesterday that I saw her.
• You'll find the keys in the kitchen. → It's in the kitchen that you'll find the keys.
• Not "It was John which broke the window." — say "It was John who broke the window.". For a person, use who (or that), not "which".
• Try it: Mei suggested the idea. Put the spotlight on Mei. (Leave out the word you don't need.) Answer: It was Mei who suggested the idea. — To spotlight a person, wrap her in It was ... who: It was Mei who suggested the idea. "Which" is for things, not people, so leave it out. For a person, use who (or that).

Negative and question clefts

The It ... that cleft also works in the negative and as a question. To deny that one part is the focus — often to correct someone — use It wasn't / isn't + the part + that / who. To ask which part is in focus, front the sentence with Was it / Is it + the part + that / who ... ? In both, keep the that / who when the focus is the one doing the action (It wasn't the noise that woke me), because dropping it leaves the second half with no subject. When the focus is the thing the action is done to, it can be left out — It was Sam I saw, alongside It was Sam that I saw — but keeping it is always safe.

• It was the noise that woke me. → It wasn't the noise that woke me — it was the light.
• The quality matters most. → It isn't the price that matters; it's the quality.
• Sam called you. → Was it Sam who called you?
• You left the keys here. → Was it here that you left the keys?
• Not "Was it Sam called you?" — say "Was it Sam who called you?". Sam is the one who did the calling, so who has to stay — without it the second half has no subject: Was it Sam who called you?
• Try it: The rain ruined the trip. Correct the mistake: it wasn't the rain. Build a negative it-cleft. (Leave out the word you don't need.) Answer: It wasn't the rain that ruined the trip. — Make the cleft negative with It wasn't ..., then keep that: It wasn't the rain that ruined the trip. The negative already sits in "wasn't," so an extra "didn't" would double it up — leave it out. This is the pattern for correcting someone: it wasn't X (it was something else).
• Try it: Anna sent the email. Ask a yes/no question: was it Anna? Build a question cleft. (Leave out the word you don't need.) Answer: Was it Anna who sent the email? — Front the question with Was it ..., then keep who: Was it Anna who sent the email? "Was it" already makes it a question, so the extra "did" isn't needed — leave it out. Anna is the one doing the sending, so who has to stay: without it, "sent the email" has no subject.

What I need is ...

Another way is to start with What + the rest, then is / was + the spotlighted part. This saves the important idea for the end.

• I need a good rest. → What I need is a good rest.
• His reaction surprised me. → What surprised me was his reaction.
• We're looking for commitment. → What we're looking for is commitment.
• Not "What I need it is a good rest." — say "What I need is a good rest.". Don't add an extra it: What I need is ..., not "What I need it is".
• Try it: His honesty impressed me. Start with What and save the surprise for the end. (Leave out the word you don't need.) Answer: What impressed me was his honesty. — Start with What ..., then was + the spotlighted part: What impressed me was his honesty. An extra "it was" here would double up the linking word, so leave it out. It's What ... was ..., with no extra it.

All I want is ... (the only thing)

To say something is the only thing, start with All + the rest, then is / was + that one thing. All is treated as a single idea here, so the linking verb is is / was, not "are / were".

• I just want to go home. → All I want is to go home.
• She only needed a little time. → All she needed was a little time.
• We're only asking for an apology. → All we're asking for is an apology.
• Not "All I want are some peace and quiet." — say "All I want is some peace and quiet.". All counts as one idea, so use is, not "are".
• Try it: I just want to go home. Say it's the only thing, starting with All. (Leave out the word you don't need.) Answer: All I want is to go home. — All + the rest takes a single linking word, is: All I want is to go home. "Are" doesn't fit after "All I want" here, so leave it out. All I want is ... means this is the only thing.