Ответ:
1. We have seen everything in this museum.
2. I don`t like this park. It is very small.
3. What a nice hat you have! When did you buy it? - I bought it last month.
4. Will you sing at the party?
5. Where are you going? - I am going to the station.
6. Where are you from? - I am from Moscow.
7. I have done my home-work - I am free now.
8. Nick has bought a very good present for his mother.