TENSES

FUTURE PERFECT

Future perfect, form
The future perfect is composed of two elements: the simple future of the verb to have (will have) + the past participle of the main verb:

Subject	will have	past participle
He	will have	finished

Affirmative
I will have left

Negative
They won't have gone

Interrogative
Will we have seen?

Interrogative negative
Won't he have arrived?

Example: to arrive, future perfect

Affirmative	Negative	Interrogative
I'll have arrived	I won't have arrived	Will I have arrived?
You'll have arrived	You won't have arrived	Will you have arrived?
He'll have arrived	She won't have arrived	Will it have arrived?
We'll have arrived	We won't have arrived	Will we have arrived?
You'll have arrived	You won't have arrived	Will you have arrived?
They'll have arrived	They won't have arrived	Will they have arrived?

Future perfect, function
The future perfect refers to a completed action in the future. When we use this tense we are projecting ourselves forward into the future and looking back at an action that will be completed some time later than now.
It is often used with a time expression using by + a point in future time.

Examples:

a. I'll have been here for six months on June 23rd.
b. By the time you read this I'll have left.
c. You will have finished your work by this time next week.