Future Perfect and Future Continuous

The information written below was taken from: 

https://learnenglish.britishcouncil.org/en/grammar-reference/future-continuous-future-perfect 

Future continuous

• 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.

Future Perfect

• 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.

More explanations here and here.

Exercises:

Over here where you have tests where you can practice.