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

A．did the villagers realize                       B．the villagers realized

C．the villagers did realized                      D．didn’t the villagers realize

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

Not until all the fish died in the river ________ how serious the problem of water pollution was．

1. A.
   did they realize
2. B.
   they did realize
3. C.
   had they realized
4. D.
   they had realized

Not until all the fish died in the river        how serious the problem of water pollution was.

       A．did they realize       B．they did realize C．had they realized     D．they had realized

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

A．did the villagers realize B．that the villagers realized

C．the villagers did realize                             D．didn’t the villagers realize