Future Perfect Continuous
Future Perfect Continuous has two different forms: "will have been doing " and "be going to have been doing." Unlike Simple Future forms, Future Perfect Continuous forms are usually interchangeable.
FORM Future Perfect Continuous with "Will"
[will have been + present participle]
FORM Future Perfect Continuous with "Be Going To"
[am/is/are + going to have been + present participle]
NOTE: It is possible to use either "will" or "be going to" to create the Future Perfect Continuous with little or no difference in meaning.Complete List of Future Perfect Continuous Forms
USE 1 Duration Before Something in the Future
We use the Future Perfect Continuous to show that something will continue up until a particular event or time in the future. "For five minutes," "for two weeks," and "since Friday" are all durations which can be used with the Future Perfect Continuous. Notice that this is related to the Present Perfect Continuous and the Past Perfect Continuous; however, with Future Perfect Continuous, the duration stops at or before a reference point in the future.
Notice in the examples above that the reference points (marked in italics) are in Simple Present rather than Simple Future. This is because these future events are in time clauses, and you cannot use future tenses in time clauses.
USE 2 Cause of Something in the Future
Using the Future Perfect Continuous before another action in the future is a good way to show cause and effect.
Future Continuous vs. Future Perfect Continuous
If you do not include a duration such as "for five minutes," "for two weeks" or "since Friday," many English speakers choose to use the Future Continuous rather than the Future Perfect Continuous. Be careful because this can change the meaning of the sentence. Future Continuous emphasizes interrupted actions, whereas Future Perfect Continuous emphasizes a duration of time before something in the future. Study the examples below to understand the difference.
REMEMBER No Future in Time Clauses
Like all future forms, the Future Perfect Continuous cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of Future Perfect Continuous, Present Perfect Continuous is used.
AND REMEMBER Non-Continuous Verbs / Mixed Verbs
It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Future Perfect Continuous with these verbs, you must use Future Perfect .
The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
ACTIVE / PASSIVE
NOTE: Passive forms of the Future Perfect Continuous are not common.
EXERCISES AND RELATED TOPICS