Unit 10 Grammar 1 Future

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We use a number of different verb forms to talk about the future (the time after now) in English. Some are:
will + verb
1: To predict:
It'll be windy tomorrow and there will be rain.
2: To express a decision on the spot about the immediate future.
Which bag do you want? - I'll take the big one.
3: To promise:
I'll come on time. I promise.
be + going to + verb
1: To talk about plans or intentions (decided before the moment of speaking).
- Do you remember that job I told you about?
I' going to accept it.
- Ah, good, when did you make up your mind about it?
2: It's is used for something in the future for which we have present evidence.
Look at the clouds. It' going to rain.