Ответ:

1. Sarah is going on holiday tomorrow. I'm sure she will enjoy it.

2. She is going to meet them at 9:00pm tomorrow.

3. There isn't any milk left in the fridge. - I know, I'm going to do the shopping this afternoon.

4. I think my sister will pass the driving test, she has practised a lot.

5. I'm going to take the kids to the seaside this spring.

6. Brad Pitt will probably win the award for Best Actor.

7. That suitcase is very heavy, I'll carry it for you.

Объяснение:

is going to - для личных намерений, когда решение уже было принято раньше

will + инфинитив - для спонтанных решений и выражения уверенности/неуверенности говорящего в будущих событиях