[Hazar]

I want to know which sentense is correct. or, is there any diffent meanings?

1. If I knew you had known that he read the book, I would ~~.
2. If I knew you had known that he had read the book, I would ~~.

3. If I knew you knew that he read the book, I would ~~.
4. If I knew you knew that he had read the book, I would ~~.

5. If I knew you know that he read the book, I would ~~.
6. If I knew you know that he had read the book, I would ~~.

They are very complexing!!