Tanmog's Classes: Future Tenses

The will - future is used

1.	to talk about future actions we can't influence or control.
2.	to foretell future actions or to express hopes, expectations, fears, offers, promises, refusals,... . Key words: I’m sure, I believe, I expect, I hope, I suppose, I think, I'm afraid, I wonder, I fear, I worry, I promise, I guess or perhaps, possibly, surely, probably, maybe
3.	with I / we for spontaneous reactions or making promises I shall is sometimes used instead of I will. (

The going to - future is used

1.	to talk about future things you intend to do, plan or decided to do
Example:
Did you know that Sarah is in hospital? No, I didn’t. I’ll visit her this afternoon. (spontaneous reaction »»» will - future) Yes, I’m going to visit her next month. (planned action »»» going to - future)
2.	to foretell future actions for which we have proofs that they are going to happen.

The present progressive is used

to talk about future things that are fixed, planned or definitely decided

The speaker must refer to the future and not to the present.

I am visiting my grandparents tomorrow.

What are you doing next Friday?

The present simple is used

to talk about times of arrivals and departures of traffic and times of events.

The train leaves at 10.20.

The bus goes at 8.30.

When does the concert begin?

http://www.english-4u.de/future_tense.htm

Tanmog's Classes