Future Perfect Continuous forms

Future Perfect Continuous Tense is built with will have been in all persons and present participle ( verb form with the ending -ing).

  Affirmative sentences contractions
I I will have been writing a letter. I'll have been writing a letter.
you You will have been writing a letter. You'll have been writing a letter.
he He will have been writing a letter. He'll have been writing a letter.
she She will have been writing a letter. She'll have been writing a letter.
it It will have been writing a letter. It'll have been writing a letter.
we We will have been writing a letter. We'll have been writing a letter.
you You will have been writing a letter. You'll have been writing a letter.
they They will have been writing a letter They'll have been writing a letter.
  Negative sentences contractions
I I will not have been writing a letter. I won't have been writing a letter.
you You will not have been writing a letter. You won't have been writing a letter.
he He will not have been writing a letter. He won't have been writing a letter.
she She will not have written a letter. She won't have written a letter.
it It will not have been writing a letter. It won't have been writing a letter.
we We will not have been writing a letter. We won't have been writing a letter.
you You will not have been writing a letter. You won't have been writing a letter.
they They will not have been writing a letter. They won't have been writing a letter.
  Questions  
I Will I have been writing a letter?  
you Will you have been writing a letter?  
he Will he have been writing a letter?  
she Will she have been writing a letter?  
it Will it have been writing a letter?  
we Will we have been writing a letter?  
you Will you have been writing a letter?  
they Will they have been writing a letter?