Future Perfect Continuous Tense

Definition

Like the future perfect tense, we use the future perfect continuous tense (also known as the future perfect progressive tense) to indicate how long something has been happening once a future moment in time is reached. It can also be used in this way to indicate the cause of a possible future result.
The most common way we create the future perfect continuous tense is by using the modal auxiliary verb will + have been + the present participle of the verb. For example:
  • “By June, I will have been living in New York for four years.”
  • “She’s going to miss half the day because she’ll have been sleeping for so long!”

Using the Future Perfect Continuous

The future perfect continuous tense is used in a very similar way to the future perfect to describe the duration of a completed future action. They both carry the same meaning when used in this way, but the future perfect continuous emphasizes the continuous nature of the action. Consider, for example, these two sentences:
  • “By the time I get there, she will have waited for over an hour.” (future perfect tense)
  • “By the time I get there, she will have been waiting for over an hour.” (future perfect continuous tense)
The meaning is technically the same in both examples above; however, the second sentence stresses the fact that she was continuously waiting during the future period by the time I get there. The change in meaning is subtle, but it adds greater depth to the sentence. Here are some other examples using the future perfect continuous tense:
  • “I will have been working on this ranch for more than half my life when I turn 40.”
  • “She’ll have been studying Japanese for four years by the time she graduates.”
  • “When the teacher comes back, we’ll have been reading for nearly two hours.”

With action verbs

Because it describes continuous, dynamic action, the future perfect continuous can only be used with action verbs; it cannot be used with stative verbs (such as linking verbs or verbs of the senses), which describe non-continuous actions. For stative verbs, we can only use the future perfect tense instead. For example:

Cause of future results

We can also use the future perfect continuous to indicate that the continuous action that finishes in the future will be the cause of something in the future. For example:
  • “I bet he’ll be hungry because he will have been studying straight through lunch.”
  • “I’m not going to have any energy for the kids because I’ll have been working so hard this week.”
  • “You’re going to look like a prune since you will have been swimming all afternoon!”

Other sentence types

Negative sentences

To describe something that will not be completed over a certain span of time into the future, we make the future perfect continuous tense negative by adding not after the modal verb will (usually contracted as won’t). For example:
  • “Why are you bringing your book to the airport? We won’t have been waiting for very long before her plane arrives.”
  • “He will not have been working here for very long if he is fired over this incident.”
However, it’s not very common to make negative constructions of the future perfect continuous tense.

Interrogative sentences

We can ask whether an action will be completed in the future after a certain duration by inverting will with the subject, as in:
  • Will they have been searching for us for very long?”
  • Will she have been working in Japan for the whole time she’s lived there?”
We can also ask about specific aspects of a future action by using different question words or phrases. Remember, we still invert will with the subject in this case:
  • Who’ll have been writing the notes for the class while the teaching assistant is absent?”
  • How long will you have been working there before your maternity leave begins?”

Other constructions

Although we most commonly use the modal verb will, there are two other ways we can form the future perfect continuous tense: be going to and shall.

Be going to

Be going to is interchangeable with will in meaning when we make the future perfect continuous tense. However, using be going to can sometimes result in a wordy, awkward construction, and it is not as common as will.
We usually contract be with the subject when we use be going to. For example:
  • “She’s going to have been working for nearly 18 hours by the time she’s finished with her shift tonight.”
  • “I’m going to have been reading this book for nearly six months if I don’t finish it soon!”

Shall

We can also use the modal verb shall instead of will to form the future perfect continuous tense in more formal speech or writing. For example:
  • “By next spring, I shall have been living on my own for nearly a decade.”
  • “The students shall have been reading their books for the entire period.”
  • “You shall have been hearing, no doubt, the unflattering remarks made about my character.”
However, this creates a very formal tone that is not common in modern English. Among the three options available, will is the most common way to construct of the future perfect continuous tense.
Quiz

1. What form of the main verb is used to create the future perfect continuous tense?





2. Which of the following is a function of the future perfect continuous tense?








3. Where does not appear in a negative sentence in the future perfect continuous tense?





4. Which of the following is the most common way to form the future perfect tense?





5. Which type of verb cannot be used in the future perfect continuous tense?








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