Future tenses
Will and going to; shall
You use going to instead of will when you predict that something will happen in the future because you have some evidence for it now.
What's the matter with him? – He thinks he's going to throw up.
However, if you make a prediction based on your opinion or your past experience you use will.
I imagine the stadium will be full for the concert on Sunday.
When you talk about intentions or decisions about the future that were made sometime before you report them, usegoing to:
Jane told me that she's going to visit her friends.
However, note that in a formal style, you use will rather than going to when you talk about future events that have been previously arranged in some detail:
Breakfast will begin at 8:00 am.
When you state a decision made at the moment of speaking, use will:
I'm tired. I think I'll go to sleep now.
Shall is used mostly in the questions shall I / shall we…?
In spoken English we normally use I'll and we'll:
I'll probably go to Spain.
The negative of shall is shall not or shan't:
I shan't be here tomorrow. (or I won't be…)
Do not use shall / shan't with other subjects he / she / it / you / they when you talk about the future:
He will be very upset. (not He shall be)
Future Continuous (will be doing)
You use Future Continuous when you talk about an activity or event going on at a particular time or over a particular period of time in the future:
The jet will be traveling at twice the speed of sound when it passes over us.
With the Future Continuous you normally mention the future time:
She will be taking up her position at the company in September.
Future Continuous and Present Continuous for the future
You can often use either the Future Continuous or the Present Continuous when you talk about planned activities or events in the future:
We will be leaving / are leaving for London at 8:00 am.
The Present Continuous is preferred to talk about surprising or unexpected activities or events:
Have you heard the news? Professor Davis is leaving! (rather than …will be leaving)
You use will be doing to talk about complete actions in the future:
What time will your parents be arriving today?
Future Perfect
You use will have done to say that something will already be complete or achieved by a particular point in the future:
By the time you get home I will have cleaned the house from top to bottom.
Future Perfect Continuous
You use the Future Perfect Continuous to emphasize how long something has been going on by a particular point in the future:
Next month I will have been working in this company for 20 years.
In sentences with the Future Perfect Continuous you usually indicate both a particular point in the future ( On Monday…) and the period of time before this point (… for a year, …20 years).
Notice that you don't usually use the Future Perfect Continuous with verbs describing states:
Next week I will have known Dick for 30 years.
Present Simple ( I do ) and future meaning
You use the Present Simple when you talk about timetables, programs etc. for public transportation, cinemas etc.:
What time does the movie begin?
You can use the Present Simple for people if their plans are fixed like a timetable:
What time do you finish school tomorrow?
The Continuous is more usual for personal arrangements:
What time are you meeting Pam tomorrow?