We use the future perfect continuous when we describe an action (quite a long one) that has begun sometime in the past, present, or future, and is expected to continue in the future. In this case, we are projecting ourselves forward in time and looking back at the duration of that action.
When Peter turns 40, he will have been painting for 35 years
The future perfect continuous is formed with will + have + been + the present participle. Questions are formed by inverting the subject and will. Negatives are formed with not. Contracted forms are used.
(+) At 6 o'clock I will have been waiting here for an hour / At that time I'll have been waiting here for an hour
(-) I won't have been waiting here for an hour at 6 o'clock (?) Will I have been waiting here for an hour at 6 o'clock?
We often use by + time expression with the future perfect continuous to show that the situation has begun sometime in the past, present, or future, and is expected to continue in the future.
By 2025 he'll have been living in London for 10 years
We can also use when, as soon as, before, or by the time to show the sequence of events. In this case, use the present simple tense in the parts with when, by the time etc.
When I complete my studies, I'll have been learning English for 17 years
Remember that non-continuous verbs (e.g. to love, hate, know, want, etc.) are not used in any continuous tenses. Use the future perfect instead.
In March I'll have been knowing you for a year.In March I'll have known you for a year
By this time next year I will have been wanting to start my own business for a decade.
–I've just realized that by the time they finish their trip, they'll have been hiking for more that 25 days.
–Yeah, I know! And they won't have been sleeping in bed or having a shower in almost a month!
–Yeah. Well, at least they won't be that picky about the food then! When we pick them up, they will have been eating canned food for weeks.
–Maybe taking them straight to the buffet is a better idea...
Make sentences using the words.
we - to wait - for over an hour - by the time Kim - to arrive .
how long - you - to study - when you - to graduate?
we - to drive - for 12 hours - when we - to get - to Berlin.
my sister - to teach - for more than 5 years - by the time she - to leave - for Europe.
Put the verbs into the future perfect (I will have done) or the future perfect continuous (I will have been doing) form.
I/to get ready) .................... by then. Kate/to lose) .................... all her motivation before the end of the semester. Jack/to wait) .................... for her to say "Yes" for 2 years next month. Answer the questions.