Prince  William and The Duchess of Cambridge

Form

will + have + been + verb + ing

Affirmative Yes/no questions Negatives

I will have been working

for seven years.

Will you have been working...?

Yes, I will./ No, I won’t.

He will not have been working...

Usage

We can use the future perfect continuous to say how long something will have continued by a certain time.

By the time you get here, I’ll have been working for six hours.

Compare this to the future perfect tense. What general rule could be applied to the teaching of the two forms?

The future perfect continuous often includes an adverbial expression that begins with by.

By next week...

By this time tomorrow,...

Typical student errors/mistakes

Form: Next Christmas I’ll have been learn English for four years.

By this time tomorrow, I’ll be drinking for twelve hours.