Ответ:

1. I'm going to get a new bike next weekend. I'm not going to get a new bike tomorrow.
2. We are going to take an exam this afternoon. We are not going to take an exam in a few days.
3. I am going to send an email tonight. I am not going to write a letter tonight.
4. They are going to move house next week. They are not going to move house tomorrow.
5. She is going to do aerobics this evening. She is not going to go running this evening.
6. I am going to start university next year. I am not going to start university next month.