选择正确的句子, 将其序号填在横线上

A. I'm going to visit my uncle. B. No, I don't. C. there was a nice river. D. The air is not so fresh. E. There were no cars at all.

Jack：What are you going to do on May Day, Ben?

Ben：. He lives in a village.

Jack：How is there now?

Ben：There are a lot of tall buildings. There are many cars, too.

Jack：How was there before?

Ben：It was so nice before. There were only some houses..

Jack：What did you do then?

Ben：I often swam in it because .

Jack：Do you often go swimming now?

Ben：. The river isn't clean.

Jack：I hope it will be better.