Betty: I went shopping in the city centre with my family last week.

Tony: Did you have a good time?

Betty: Yes, I did, but there was a lot of traffic on the way there. Then there were too many people and not enough space. It was impossible to move. And there was a lot of noise.

Tony: Well, Beijing is a big city.

Betty: Yes, it is. It has a population of about twenty million.

Tony: Twenty million！Does Beijing have the largest population in China?

Betty: No, it doesn’t. Chongqing has the largest population in China. More than thirty–three million people live there .

Tony: Really? That’s a lot of people!

Betty: Yes, and there’s a lot more pollution in the air.