根据下面所提供的对话情景，选择恰当的句子完成对话，使其意义连贯、完整。

A: Wang Lin , which city do you know will host（主办）the 2008 Olympics ?
B: Beijing .
A:
B: Lots of things , such as more roads , more buildings and more visitors .
A:
B: Yes .
A:
B: Of course .
A: What do you mean ?
B: There is still a lot of work to do . For example , we have to make the city clean and have less pollution .
A: I agree .