By the time he realizes he ______ into a trap, it’ll be too late for him to do anything about it.
It was his nervousness in the interview ____probably lost him his job.
It was what he meant rather than what he said ______ annoyed me.
It might have been John _____ bought a present for Mary yesterday.
What is it _____ his daughter needs most?
Who was it _____ saved the drowning girl?