It was … that …
RuleThe it-cleft (It is/was + X + that/who …) spotlights X by splitting the sentence.
Curiosity
"John called yesterday." How do you stress that it was JOHN, not someone else?
Intuition
The cleft splits one sentence to shine a spotlight on one part: "It was + [spotlight] + that + [the rest]." Whatever sits between "It was" and "that" gets the emphasis.
Visualization
See the parts: the "It was" frame and the emphasized element between it and "that" are highlighted. The relation: "It was + [emphasis] + who/that + rest."
The element between "It was" and "that" is emphasized.
It wasthe managerwhoapproved the budget
Essence
It is/was + emphasized element + that (who for people). You can emphasize a subject, object, or adverbial (It was yesterday that he called). You cannot cleft the verb. There is also the pseudo-cleft: "What I need is time." TOEIC tests the it…that frame and that vs who.
Examples
It was the new strategy that boosted sales.
It is teamwork that makes the difference.
It was in 2020 that the company expanded.
Mini-quiz
"___ the CEO who made the final decision." Which fits?