Question

Not until he got to the factory _______that he had lost his papers

1. A.
   he found
2. B.
   did he find
3. C.
   had he found
4. D.
   has he found

Answer 1

B
考查倒装句。Not until 放在句首使用部分倒装，从句不倒装，主句倒装，根据题中的时态，所以选B。