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.
[will have been + present participle]
Examples:
[am/is/are + going to have been + present participle]
Examples:
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.
Positive | Negative | Question |
I will have been sleeping. You will have been sleeping. We will have been sleeping. They will have been sleeping. He will have been sleeping. She will have been sleeping. It will have been sleeping. |
I will not have been sleeping. You will not have been sleeping. We will not have been sleeping. They will not have been sleeping. He will not have been sleeping. She will not have been sleeping. It will not have been sleeping. |
Will I have been sleeping? Will you have been sleeping? Will we have been sleeping? Will they have been sleeping? Will he have been sleeping? Will she have been sleeping? Will it have been sleeping? |
Positive | Negative | Question |
I am going to have been sleeping. You are going to have been sleeping. We are going to have been sleeping. They are going to have been sleeping. He is going to have been sleeping. She is going to have been sleeping. It is going to have been sleeping. |
I am not going to have been sleeping. You are not going to have been sleeping. We are not going to have been sleeping. They are not going to have been sleeping. He is not going to have been sleeping. She is not going to have been sleeping. It is not going to have been sleeping. |
Am I going to have been sleeping? Are you going to have been sleeping? Are we going to have been sleeping? Are they going to have been sleeping? Is he going to have been sleeping? Is she going to have been sleeping? Is it going to have been sleeping? |
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.
Examples:
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.
Using the Future Perfect Continuous before another action in the future is a good way to show cause and effect.
Examples:
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.
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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.
Examples:
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.
Examples:
The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
Examples:
NOTE: Passive forms of the Future Perfect Continuous are not common.