B2 · Lesson 22 · 25 min
Future perfect and completion
In this lesson
- I can describe something completed before a future deadline.
- I can distinguish a completed result from duration up to a future point.
Grammar in context
The repairs begin on Monday. By Friday evening, the team will have replaced every damaged tile. At that point, they will have been working on the roof for five days. The owner will inspect the finished roof on Saturday.
Which sentence counts completed work? Which measures the duration of the activity up to Friday evening?
Look back from a future point
The future perfect simple uses will have plus a past participle. It presents an action as complete by a future reference point: by Friday, we will have finished. By usually means no later than the stated time; before places the completion earlier. The speaker is looking back from an imagined future position. This differs from the future continuous, which views an activity as in progress around that future moment rather than explicitly complete.
- By the end of the month, the team will have checked all the records.
- The guests will have left before the cleaners arrive.
Negatives and questions
For a negative, use will not have plus a past participle, or won’t have. In questions, put will before the subject and leave have before the past participle. Use the past participle even with irregular verbs: written, taken, done. A future time clause introduced by before, when or by the time normally uses a present form rather than will when it identifies the future event used as the reference point.
- Will you have written the summary by noon?
- We won’t have completed the checks when the manager arrives.
Measure duration with the continuous form
The future perfect continuous uses will have been plus an -ing form to focus on duration up to a future point. A for-phrase often states the length of time. The future perfect simple can also describe duration with suitable verbs, especially states such as know; do not automatically choose continuous just because for appears. When both forms are possible, the simple tends to foreground a result or situation, while the continuous foregrounds the activity and its duration.
- By six, I will have been waiting for two hours.
- Next June, I will have known my neighbour for ten years.
Common mistakes
Compare the incorrect and corrected forms.
Avoid
By Tuesday, she will have wrote the report.
Use
By Tuesday, she will have written the report.
Have needs the past participle written.
Avoid
By next year, I will have been knowing him for a decade.
Use
By next year, I will have known him for a decade.
Know is stative in this meaning and normally uses the simple perfect.
Put it into practice
Try the exercises, write your own examples and check your understanding.