Future perfect progressive (continuous) refers to a progressive event that will be completed at some point in the future. Here are the forms and uses of this tense.
the future perfect of the verb "to be": (will have been) + the present participle of the main verb (base + ing)
Like the future perfect simple, this form is used to project ourselves forward in time and to look back. It refers to events or actions that are currently unfinished but will be finished at some future time. It is most often used with a time expression.
- I will have been waiting here for three hours by six o'clock.
- By 2001 I will have been living in London for sixteen years.
- When I finish this course, I will have been learning English for twenty years.
- Next year I will have been working here for four years.
- When I come at 6:00, will you have been practicing long?
It is used to show that an event will continue up until a particular event or time in the future. It is mostly used with an expression such as:
- for five minutes
- for two weeks
These expressions indicate durations.
- She will have been working for over 8 hours by the time her children arrive.
- He will have been studying English for three years next month.