Here are the answers to the transformations based on the sentences provided:

1. I can’t cook and John can’t either.
=> Neither can John.

2. That’s the strangest film I’ve ever seen.
=> I’ve never seen a stranger film.

3. When you phoned me, it was my lunchtime.
=> I was having lunch when you phoned me.

4. Diana finds it easy to make friends.
=> Diana has no trouble making friends.

5. I only recognized him when he came into the light.
=> Not until he came into the light did I recognize him.