Future perfect

1. Future perfect

Be at the airport in an hour, I will have arrived by then.

It's said that by the end of the century, sea levels will have risen between 18 and 59 cm.

2. Structure of future perfect

• Affirmative form
  

  Subject	Auxiliary	Have	Verb (past participle)	Examples
  I	will 'll	have	finished	I will have finished by Monday.
  You				You will have finished by Monday.
  He				He will have finished by Monday.
  She				She will have finished by Monday.
  It				It will have finished by Monday.
  We				We will have finished by Monday.
  You				You will have finished by Monday.
  They				They will have finished by Monday.

• Negative form
  

  Subject	Auxiliary	Have	Verb (past participle)	Examples
  I	will not won't	have	finished	I won't have finished by Monday.
  You				You won't have finished by Monday.
  He				He won't have finished by Monday.
  She				She won't have finished by Monday.
  It				It won't have finished by Monday.
  We				We won't have finished by Monday.
  You				You won't have finished by Monday.
  They				They won't have finished by Monday.

• Interrogative form
  

  Auxiliary	Subject	Have	Verb (past participle)	Examples
  Will	I	have	finished?	Will I have finished by Monday?
  	You			Will you have finished by Monday?
  	He			Will he have finished by Monday?
  	She			Will she have finished by Monday?
  	It			Will it have finished by Monday?
  	We			Will we have finished by Monday?
  	You			Will you have finished by Monday?
  	They			Will they have finished by Monday?

Interrogative sentences in future perfect have their own short answers.

- Will you have tidied your bedroom before I come back?

- Yes, I will.

3. How do we use the future perfect?

The future perfect is used for:

• An action that will be completed before a particular time in the future, or another action that will occur in the future.
  
  He will have finished the fence by the weekend.

  By the time I get to work, the meeting will have already started.
• An action that will be completed in the near past. Usually applied to make deductions.
  
  Will the jury have reached a verdict by now?

  The plane will have taken off by now.
• An action will have taken place over a period of time up to a particular point in the future.
  
  Next month we'll have been friends for 50 years.

  Tomorrow they'll have been in China for 2 weeks
• Some expressions that are usually used with the future perfect are the following:
  

  Expresiones
  By the time
  By Monday / next month
  By now / then
  By the year 2050
  Before / not... until

Remember!