1) – Have you got tickets to the train?
— Perhaps, we (are going to buy/will buy) them next week.

2) – What present are you going to give Mary for her birthday?
— We (give/are going to give) her a computer game and a cake.

3) – Are you going to the theater with your class next week?
— I don`t know yet. Maybe I (will visit/ are visiting) my grandparents.

4) – Will you come to the party?
— I think I (am coming/will come).