· The teacher won't be very happy.
· I'm sure you'll pass all your exams
If we are not so certain about the future, we use 'will' with expressions such as 'probably', 'possibly', 'I think', 'I hope'.
· I don’t think I’ll go out tonight.
· I promise I won’t tell Montse what you’ve just said
· She'll probably pass her driving test this year.
At the moment of making a decision, use 'will'.
· I’ll have a mushroom pizza, please.
· I know! I’ll send him an email.
Once you have made the decision, talk about it using 'going to'.
· I'll call Joan to let him know. Paula, I need Joan's number.
I'm going to call him about the meeting.
· She isn’t going to study at University next year.
To make a future prediction based on evidence in the present situation, use 'going to'.
· Not a cloud in the sky. It's going to be a nice day.
· Look at the queue. We're not going to get in for hours.
· The traffic is terrible. We're going to miss our flight.
· That boy can’t skateboard. He’s going to fall over.