Not only_______polluted but________crowded.

A.was the city,were the streets

B.the city was,were the streets

C.was the city,the streets were

D.the city was,the streets were

答案及解析： C

解析：

本题考查倒装结构。not only … but also…结构，not only部分主谓倒装，but also部分不倒装，故选C。