Not until I went through his paper _________ what rapid progress he had made in writing.

Not until I went through his paper _________ what rapid progress he had made in writing.

1. A.
   I did find
2. B.
   did I find
3. C.
   I had found
4. D.
   was I found

Not until I went through his paper _________ what rapid progress he had made in writing.

  A. I did find  B. did I find        C. I had found     D. was I found

Not until I went through his paper _________ what rapid progress he had made in writing.

 Not until I went through his paper _________ what rapid progress he had made in writing.

  A. I did find         B. did I find               C. I had found     D. was I found