Answer:
Step-by-step explanation:
1) When I eat this, I will need to do lots of exercise to burn off the calories.
2) When the school year finishes, we will have done about 300 hours of homework.
3) When I save enough money, I will start my own business.
4) By the time you send those invitations, the party will have finished.
5) When you tidy your room, I will give you your pocket money.