Grammar · Talking About the Future
Future Perfect
Will have done or will be doing? Learn how to look back from a point in the future at something already finished, with the film Tenet.
Grammar › Talking About the Future › Future Perfect
The rule in one sentenceUse will have + past participle for something that will already be finished before a point in the future, and will be + -ing for something that will still be in progress at that point.
About the film
Tenet is a 2020 science-fiction thriller directed by Christopher Nolan. After a dangerous mission at an opera house in Kyiv, a CIA agent known only as the Protagonist is recruited by a secret organisation and shown bullets that seem to travel backwards through time. Long before he fully understands how they work, he will have travelled to Mumbai, teamed up with a mysterious partner called Neil and started following a powerful Russian businessman, Andrei Sator.
What does it do?
This form lets you jump ahead to a moment in the future and look back from there. From that imaginary point, you check what is already complete. The action itself can happen at any time before that moment; the grammar only cares that it is finished by then.
There is a joke among fans that Tenet is a film where, by the time you understand it, it will already have happened. That sentence is a perfect example: the understanding comes later, and the event is already complete. Compare it with will be + -ing, which drops you into the middle of an action that is still going on at that future moment.
Look at the words that begin the first two tiles: by the time, by tomorrow. The word by works like a deadline – the action is complete before the deadline arrives. The last two tiles use at noon and all evening, which point to an action still happening, so will be + -ing fits better.
In speech, the long forms are usually shortened:
At ten o’clock, the team will be planning the mission. (still working on it at ten)
By ten o’clock, the team will have planned the mission. (the plan is ready before ten)
One small word changes the picture. At puts you inside the action; by puts you after it, looking back at a finished job.
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
How to make it
will have + past participle — finished by then
By Friday, Neil will have booked the flights.
The Protagonist won’t have understood everything by then.
won’t have + past participleWill Laura have tested every bullet by the morning?
Will + subject + have + past participlewill be + -ing — still happening
At noon, he will be flying to Mumbai.
Neil won’t be sleeping much tonight.
won’t be + verb-ingWill you be watching Tenet again this weekend?
Will + subject + be + verb-ingWhen to use each one
will have + past participle
will be + -ing
Words that help: finished or still happening?
The preposition is often the biggest clue. By and before point to a deadline; at, all and while point to an action that is still in progress.
will have done → finished by then
will be doing → still happening
Common mistakes
❌ By Friday, Neil will have book the flights.
✅ By Friday, Neil will have booked the flights.
After will have, you need the past participle, not the base form.
❌ By your second viewing, you will have understand much more.
✅ By your second viewing, you will have understood much more.
Understand is irregular: understand – understood – understood.
❌ By the time he will arrive, the meeting will have started.
✅ By the time he arrives, the meeting will have started.
After by the time, use the present simple, even for the future.
❌ By next week, the Protagonist will has learned a lot.
✅ By next week, the Protagonist will have learned a lot.
Will never changes, and it is always followed by have, never has.
One more thing
This part is a little harder. You can come back to it later.
The future perfect can also make a confident guess about the past or present. Although it looks like a future form, will have + past participle is often used to say that you are almost sure something has already happened, even though you can’t check it right now. Words like already and by now usually appear close to the verb.
✅ Neil will have heard the news by now. (I’m fairly sure he has heard it)
✅ By the time you understand it, it will already have happened. (already can also go after have: will have already happened)
This is a favourite trick of detectives and critics alike: You’ll have noticed that the film plays with time.
Practice: choose the right form
Eight questions. Choose one answer. You get the answer, and why.
1. By Friday, Neil ___ the flights.
By Friday is a deadline, and the job is complete → will have + past participle.
2. At noon tomorrow, the Protagonist ___ to Mumbai.
At noon he is in the air, so the action is in progress → will be + -ing.
3. By the time you ___ the film twice, you will have understood much more.
After by the time, use the present simple.
4. By the end of the day, Laura ___ every bullet.
After will have, the verb needs its past participle.
5. ___ Neil ___ the plan by tomorrow?
The question keeps have: Will + subject + have + past participle.
6. It’s late – the team ___ home by now.
A confident guess about something already complete → will have gone.
7. By next year, I ___ Tenet four times.
Counting up to a future point → will have + past participle.
8. This time next week, we ___ the film again.
This time next week points to an action in progress → will be + -ing.
Your turn
Choose one ending. Then listen to your sentence.
Every sentence here is correct. Each one looks back from a future moment at something already finished. Say it out loud too!
Keep going
More lessons
Practise listening at your level
Hear this grammar used for real — Advanced English listening practice. Full movie reviews in slow, clear English, levelled for Advanced learners. One new episode every week, free, with a transcript. AdvancedFree playlistWatch on YouTube