The future continuous (will be + ‘ing’ form) and the future perfect (will have + past participle) tenses are used to talk about events in the future.
- Don’t ring at 8 o’clock. I’ll be watching Who Wants to be a Millionaire.
- This time tomorrow we’ll be sitting on the beach. I can’t wait!
We use the future continuous to talk about something that will be in progress at or around a time in the future.
- Don’t phone grandma now, she’ll be having dinner.
- The kids are very quiet. They’ll be doing something wrong, I know it!
These sentences are not about the future but we can use the future continuous to talk about what we assume is happening at the moment.
- Do you think you will have finished it by next Thursday?
- In 5 years time I’ll have finished university and I’ll be able to earn some money at last.
We use the future perfect to say that something will be finished by a particular time in the future.
We often use the future perfect with ‘by’ or ‘in’
- I think astronauts will have landed on Mars by the year 2020.
- I’ll have finished in an hour and then you can use the computer.
‘By’ means ‘not later than a particular time’ and ‘in’ means 'within a period of time’. We don’t know exactly when something will finish.
- I promise I’ll have done all the work by next Saturday.
We don’t know exactly when he will finish the work – maybe Thursday, maybe Friday – but definitely before Saturday.