The future perfect continuous is used to project ourselves forward in time and to look back. It refers to events or actions in a time between now and some future time are unfinished. It is most often used with a time expression.
The future perfect continuous is composed of two elements:
The future perfect of the verb "to be" (will have been) + the present participle of the main verb (base + ing)
- They will have been living in France since 2007.
- Will it have been raining for three days?
- By 2015, he will have been living in that house for 10 years.
- Next month she will have been working here for 7 years.
- When his father returned home at 8.00 p.m, will he have been learning English for four hours.