The future perfect continuous tense, sometimes referred to as the future perfect progressive, is a crucial aspect of English grammar. It is used to express actions that will continue until a specific point in the future. This guide offers a detailed explanation of the structure, usage, and examples of the future perfect continuous tense. Additionally, you will find practice exercises to reinforce your understanding of this fundamental aspect of English grammar.
Structure of Future Perfect Continuous Tense:
The future perfect continuous tense comes in two forms: “will have been doing” and “be going to have been doing.” Both forms can typically be used interchangeably.
- Affirmative sentences: Subject + will have been/be going to have been + present participle (base verb + ing) + (time duration) Example: By the end of this month, she will have been working at the company for five years.
- Negative sentences: Subject + will not have been/be not going to have been + present participle (base verb + ing) + (time duration) Example: Before they move back to their hometown, they will not have been living in the city for long.
- Interrogative sentences (questions): Will/Is/Are + subject + have been + present participle (base verb + ing) + (time duration) + ? Example: When you finally go to bed, will you have been studying for the exam all night?
- Interrogative-negative sentences: Will/Is/Are + subject + not + have been + present participle (base verb + ing) + (time duration) + ? Example: When it finally arrives, will they not have been waiting for the bus for over an hour?
Using the Future Perfect Continuous Tense:
- Duration before something in the future: The future perfect continuous tense is employed to indicate that something will continue until a particular event or time in the future. This tense is related to the present perfect continuous and past perfect continuous, but the duration stops at or before a reference point in the future. Phrases like “for five minutes,” “for two weeks,” and “since Friday” can all be used with the future perfect continuous tense.
Examples:
- By the time Thomas arrives, they will have been talking for over an hour.
- When it finally closes, she is going to have been working at that company for three years.
- Cause of something in the future: To show cause and effect, use the future perfect continuous tense before another action in the future.
Important Points to Remember:
- Non-continuous verbs: These verbs cannot be used in continuous tenses, including the future perfect continuous tense. Instead, use the future perfect tense for such verbs.
Example:
- She will have known him for years before they become close friends. (Correct)
- Adverb placement: For grammar adverbs like always, only, never, ever, still, and just, follow these examples for correct placement:
- They will only have been traveling for an hour when they encounter a roadblock.
- Will you just have been discussing the problem when the boss walks in?
- Active/Passive Voice: Active: The team will have been preparing the presentation for weeks before the conference. Passive: The presentation will have been being prepared by the team for weeks before the conference. (Note: Passive forms of the future perfect continuous are not common.)
- Future Continuous vs. Future Perfect Continuous:
It is crucial to differentiate between future continuous and future perfect continuous tenses, as using them interchangeably can alter the meaning of a sentence. Future continuous emphasizes interrupted actions, while future perfect continuous emphasizes a duration of time before something in the future. To understand the difference, study the examples below:
- 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 the future perfect continuous, use the present perfect continuous in these cases.
