The Future Perfect Continuous tense:

Affirmative:

Subject + will have been + verb (with -ing)

I will have been studying for three hours.

Negative:

Subject + will not have been + verb (with -ing)

She will not have been working on this project for two weeks.

Question:

Will + subject + have been + verb (with -ing)?

Will they have been practicing for the competition?

In Future Perfect Continuous , will have been is used as the auxiliary verb along with the present participle form (-ing) of the main verb.

When making a negative sentence, not is added after the auxiliary verb will.

For questions, will is placed at the beginning of the sentence, followed by the subject, then have been, and finally the verb with -ing.

Usage:

We use Perfect Continuous to talk about an action that will be ongoing and in progress at a specified point in the future.

We use this tense to describe actions that will have started in the future and will be ongoing up until a specific time in the future.

For example, By 10 p.m. tonight, I will have been studying for five hours.

This sentence indicates that the action of studying will start in the future and will continue up until a specific point in the future, which is 10 p.m. tonight.

Future Perfect Continuous is also used to make predictions about the future, to talk about the duration of an action that will be ongoing up until a specific point in the future, and to describe ongoing actions that will be in progress at a particular time in the future.

Overall, we use Future Perfect Continuous to talk about ongoing actions that will be in progress up until a specific point in the future.

Usage Situation	Example Sentences
Ongoing action that will be in progress up until a specific point in the future	By this time tomorrow, we will have been driving for 10 hours.
Making predictions about the future	They will have been living in that house for 10 years by next month.
Describing a duration of an action that will be ongoing in the future	She will have been working on this project for 3 months by next week.
Describing an action that will be in progress at a particular time in the future	They will have been running the marathon for 5 hours by noon.
Hypothetical situations in the future	If he arrives late, we will have been waiting for him for an hour.

Adverbs in Future Perfect Continuous:

What adverbs can we use in Future Perfect Continuous?

There are several adverbs that can be used in Future Perfect Continuous to give more information about the time, duration, or frequency of the ongoing action.

Some common adverbs that can be used with this tense include:

For indicates the duration of the ongoing action.

Example: By the end of the month, she will have been studying for 6 months.

By indicates the point in time when the ongoing action will end.

Example: By next week, we will have been living in this city for 5 years.

Since indicates the point in time when the ongoing action started.

Example: They will have been waiting since noon.

All day/week/month/year indicates the frequency of the ongoing action.

Example: They will have been working all day on this project.

Continuously/constantly indicates the uninterrupted nature of the ongoing action.

Example: She will have been practicing continuously for the past 3 weeks.

Click here The Future Perfect Continuous tense