What is the structure of the future perfect progressive tense?

The future perfect progressive tense is used to describe actions that will have been ongoing up to a certain point in the future. The structure of this tense is constructed as "will have been" followed by a present participle (the -ing form of a verb).

For example, in the sentence "By next year, I will have been working here for five years," the phrase "will have been working" indicates that the action of working started in the past and will continue up to a particular moment in the future (next year). This tense emphasizes not just the completion of an action, but also the duration of that action up until that future point.

The other choices do not capture this specific structure and meaning associated with the future perfect progressive tense, focusing instead on forms that describe different aspects or tenses of actions.