Should I use "who" or "that" after the person?

Both can refer to a person in an it-cleft. "Who" is a straightforward choice here. Do not add another subject pronoun after it: the focused person is already the subject of the action that follows.

Home Grammar Cleft Sentences ExercisesIt-Cleft Subject Focus Exercises (Easy)

It-Cleft Subject Focus Exercises (Easy)

B1-B2 Level

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Start by finding the person or people who perform the action. Put that subject straight after It is or It was, then add who or that and keep the rest of the original sentence.

The opening is already supplied, so do not type it again. In these sentences, It was introduces a past action and It is introduces a present fact or habit. Keep the original verb after who/that: moving the subject into focus does not mean changing the action or adding another subject pronoun. One less thing to change 😅