Mr. Black: What may happen in the future?
Kitty: Perhaps there will be more people. There may not be enough food.
Peter: I hope not. 
Kally: Perhaps there won't be enough room for everybody to live on the earth, either. 
Alice: I don't think so. Perhaps people will be able to live on the moon.
Danny : I hope so, but I don't think so.
Kally: Perhaps people will be able to live in space stations on the moon.
Peter: Perhaps they will be able to grow vegetables there.