Question

Not until all the fish died in the river ________ how serious the pollution was

1. A.
   did the villagers realize
2. B.
   the villagers realized
3. C.
   the villagers did realize
4. D.
   didn't the villagers realize

Answer 1

A
not until 放在句首时，它连接的时间状语不倒装，主句应倒装。