It-Clefts — It Is Only Now That (C2)

It is only now ___ I understand what she meant all those years ago.

It was only by chance ___ we discovered the leak before it spread.

Which cleft is correct?

It was only after the meeting ___ she told me the real reason.

It is only when the lights go out ___ the stars become visible.

It is only in retrospect ___ the warning signs become obvious.

It is only through constant practice ___ fluency is achieved.

It is only now ___ scientists have begun to grasp the scale of the change.

It was only with the director's approval ___ the project could go ahead.

Which sentence is correct?

It is only by listening carefully ___ you can detect the subtle change in tone.

It was only once the data had been verified ___ the findings were published.

It is only at moments of crisis ___ true leadership reveals itself.

It is only in the final chapter ___ the author reveals the narrator's identity.

It is only when all other options have failed ___ force should be considered.