Will be combines with many of the nouns and adjectives possible after the simple present/past of be for normal will-future uses:
It will be sunny tomorrow I'll be here by 7 [> 9.35-37] Will be can be used for deduction: That will be Helen [> 11.33]
The future perfect of 'be' as a full verb
Will have been combines with the same nouns and adjectives possible after have been for normal uses in the future perfect [> 9.43]:
How long will you have been a teacher?
By the end of next week, I will have been a teacher for 25 years Will have been can be used to mean 'lived, worked, waited':
How long will you have been with IBM?
By the end of January I will have been with IBM for six months Will have been can also be used for deduction [> 11.33]:
That will have been Roland He said he'd be back at 7
10 Be, Have, Do
There' + 'be'
10.17 Some forms of 'there' + 'be' [For there + modals > 11. 76]
The simple present the simple past
There is a man at the door There was someone to see you
There are two men at the door There were some people to see you
The present perfect the past perfect
There has been an accident He said there had been an accident
There have been a lot of enquiries a lot of enquiries
The simple future the future perfect
There will be a letter for you There will have been a definite
tomorrow result before Friday
tag questions [> 13. 17-22]
There is a big match on TV tonight isn t there7
There has been some awful weather lately hasn t there7