Not only_______polluted but________crowded.
A.was the city,were the streetsB.the city was,were the streetsC.was the city,the streets wereD.the city was,the streets were在线课程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。