根据对话内容从方框中选择能填入空白处的最佳选项补全对话，期中有两项多余

A: Good morning Gao Shan

B. I'm thinking about our life in 50 years

A: That's interesting.

B. I think there will be more people and cars.

A: I agree with you.

B: There will be less clean water.

A: That's too bad. We must do something to save ourselves and our earth.

B: You're right.

A: I've no idea.

B: That's a good idea!

A. Anything else? B. I can't believe it! C. Let's ask our teacher. D. But what can we do? E. What are you doing? F. What's the population of our city? G. What do you think will it be like in 50 years?