English has two true tenses, past and present (sometimes analysed as non-past).
Although we often talk about "future tenses", technically there are no future tenses in English - only different ways of talking about the future, using special constructions, other tenses or modal verbs.
Simple future has 4 different forms in English:
・Present simple (do)
・Present continuous (be doing)
・(be) going to do
・will/shall ('ll) do
We sometimes use the simple present form to discuss future events.
Especially when talking about official events that happen at a set time such as timetables, meetings,itineraries, programmes etc.
We often use the present continuous tense to talk about the future. Of course, we normally use the present continuous to talk about action happening in the present, but if we add a future word, we can use it to talk about the future.
(By "future word" we mean words or expressions like tomorrow, next week, in June. The future word may be clearly expressed or understood from the context.)
Present Continuous is used to state future events or actions when it is clearly stated or understood that the action or event is in the future.
Pre-arranged Plans -to describe planes that have be arranged before the time of speaking.
I'm doing something (future word)
= I've already decided and arranged to do it.
・We are traveling to Europe next week.
・it is not used for official purposes.
・the subject of the sentence must be a person, not a thing.
・the present continuous can't be used to predict a future event or action, based on a present event or action.
・static verbs are not used.
Sometimes there is no real difference between an intention "going to" and a plan (present continuous). In this case, it doen't matter which we use.
・We're going to paint the bedroom tomorrow.
・We're painting the bedroom tomorrow.
I'm going to do sth
=I've already decided to do it, I intend to do it.
The "going to" construction is used when we have the intention to do something before we speak.
We have already made a decision before speaking.
・When are you going to go on holiday?
・We are not going to work next week.
・We're going to buy a new car next year.
The "going to" is often used to make a prediction about the future.
Our prediction is based on evidence. We are saying what seems sure to happen.
・The sky is very black.(evidence) It is going to rain!
・It's 8.30!(evidence) You're going to miss the train!
・I crashed the company car.(evidence) My boss isn't going to be very happy!
・Watch out! He's going to crash into that tree!
・It looks as though Manchester United are going to win the European cup.
・I think my friend Louise is going to have a baby.
When we give information about the future or predict future events that are not certain, we usually useshall/will.
One of the most common ways to talk about the future is with will.
We often call this the "future simple tense", but technically there are no future tenses in English. In this construction, the word "will" is a modal auxiliary verb.
I will do
=I decided to do sth at the time of speaking
We use "will" when there is no prior plan or decision to do something before we speak. We make the decision at the time of speaking.
・Hold on. I'll get a pen.
・We will see what we can do to help you.
・Maybe we'll stay in and watch television tonight.
We often use will with the verb think:
・I think I'll go to the gym tomorrow.
・I think I'll have a holiday next year.
・I don't think I'll buy that car.
We often use "will" to make a prediction about the future. Again, there is no firm plan. We are saying what we think will happen.
・It will rain tomorrow.
・People won't go to Jupiter before the 22nd century.
・Who do you think will get the job?
The verb "be" is an exception with will.
Even when we have a very firm plan, and we are not speaking spontaneously, we can use will with "be".
・I will be in London tomorrow.
・There will be 50 people at the party.
・The meeting will be at 9.30 am.
"Will" vs. "Going to" for prediction
We use "will" for prediction when we have no real evidence:
"It will rain tomorrow."
(It's my feeling but I can't be sure.)
We use "going to" for prediction when there is some real evidence:
"It's going to rain."(There's a big, black cloud in the sky and if it doesn't rain I'll be very surprised. The possibility of rain is high.)
"Shall" is only used with "I" and "we" normally.
In other words, "shall" is normally not used " with " you/he/she/it/ they/ "
・I shall be late this evening. (or I will be)
・We shall probably go to Scotland in the summer. ( or We will probably go)
・I shall grow old some day. In England, it would be perfectly normal to say,
“I shall have tea with my grandmother tomorrow.”
In America, that would sound odd. We Americans would be more likely to have coffee and to say,
“I will take my grandmother out for a latte tomorrow.”
"Shall" is about one fourth as common relative to will in North America as in the UK. Some in North America may consider it formal or even pompous.
Check the detail → http://en.wikipedia.org/wiki/Shall_and_will
The future continuous is used to talk about activities that will be happening at a particular time or over a particular time in the future.
We can make the future continuous in two ways:
1- Will be doing -
"・I will be waiting outside the station for you to arrive".
2 - Be going to be doing -
"・I am going to be waiting outside the station for you to arrive."
Both of these expressions have the same meaning and are interchangeable.
The only difference is that "will" shows that a future plan was made at the time of speaking. "Be going to" shows that a decision about the future had already been made.
They both show what will be happening at a time in the future. It does not tell us a starting or finishing time.
When we use the future continuous tense, our listener usually knows or understands what time we are talking about.
It is often used with a time clause (while, when + simple present) in combination.
・She will be working hard while he is enjoying himself on vacation.
Like all future tenses, the Future Continuous cannot be used in a time clauses such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of Future Continuous, Present Continuous is used.
am going to be finishingmy homework, she is going to make dinner.
・While I am finishing my homework, she is going to make dinner.
We use the future perfect to say that something will have been done, completed or achieved by a certain time in the future.
Future Perfect has two different forms:
・"will have done"
・"be going to have done"
Unlike Simple Future forms, Future Perfect forms are usually interchangeable.
・You will have perfected your English by the time you come back from the U.S.
・Will you have perfected your English by the time you come back from the U.S.?
・You will not have perfected your English by the time you come back from the U.S.
・You are going to have perfected your English by the time you come back from the U.S.
・Are you going to have perfected your English by the time you come back from the U.S.?
・You are not going to have perfected your English by the time you come back from the U.S.
1 Completed Action Before Something in the Future
The Future Perfect expresses the idea that something will occur before another action in the future. It can also show that something will happen before a specific time in the future.
・By next November, I will have received my promotion.
・By the time he gets home, she is going to have cleaned the entire house.
・I am not going to have finished this test by 3 o'clock.
・Will she have learned enough Chinese to communicate before she moves to Beijing?
・Sam is probably going to have completed the proposal by the time he leaves this afternoon.
・By the time I finish this course, I will have taken ten tests.
・How many countries are you going to have visited by the time you turn 50?
2 Duration Before Something in the Future (Stative verb)
With Stative verbs, we use the Future Perfect to show that something will continue up until another action in the future.
・I will have been in London for six months by the time I leave.
・By Monday, Susan is going to have had my book for a week.
・Next year I will not have seen my brother for 2 years.
Future Perfect Continuous has two different forms:
・"will have been doing "
・"be going to have been doing"
Unlike Simple Future forms, Future Perfect Continuous forms are usually interchangeable.
1 Duration Before Something in the Future
We use the Future Perfect Continuous to show that something will continue up until a particular event or time in the future.
"For five minutes," "for two weeks," and "since Friday" are all durations which can be used with the Future Perfect Continuous.
Notice that this is related to the Present Perfect Continuous and the Past Perfect Continuous; however, with Future Perfect Continuous, the duration stops at or before a reference point in the future.
・They will have been talking for over an hour by the time Thomas arrives.
・She is going to have been working at that company for three years when it finally closes.
・James will have been teaching at the university for more than a year by the time he leaves for Asia.
・How long will you have been studying when you graduate?
・We are going to have been driving for over three days straight when we get to Anchorage.
・A: When you finish your English course, will you have been living in New Zealand for over a year?
・B: No, I will not have been living here that long.
2 Cause of Something in the Future
Using the Future Perfect Continuous before another action in the future is a good way to show cause andeffect.
・Jason will be tired when he gets home because he will have been jogging for over an hour.
・Claudia's English will be perfect when she returns to Germany because she is going to have been studying English in the United States for over two years.
Future Continuous vs. Future Perfect Continuous
If you do not include a duration such as "for five minutes," "for two weeks" or "since Friday," many English speakers choose to use the Future Continuous rather than the Future Perfect Continuous.
Be careful because this can change the meaning of the sentence.
Future Continuous emphasizes interrupted actions, whereas Future Perfect Continuous emphasizes a duration of time before something in the future. Study the examples below to understand the difference.
・He will be tired because he will be exercising so hard.
This sentence emphasizes that he will be tired because he will be exercising at that exact moment in the future.
・He will be tired because he will have been exercising so hard.
This sentence emphasizes that he will be tired because he will have been exercising for a period of time.
It is possible that he will still be exercising at that moment OR that he will just have finished.