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

A．the villagers realize       

B．did the villagers realize   

C．didn’t the villagers realize  

D．the villagers did realize

2．Not only ____ polluted but _____ crowded．

A．was the city; were the streets

B．the city was; were the streets

C．the city was; the streets were

D．was the city; the streets were