The future perfect continuous tense shows that the action will be going on before it will be finished at a certain future time;
E.g.
* They will have been arguing whole day.
* I shall have been reading two hours.
* The class teachers will have been preparing progress charts of the students.
* The shopkeeper will have been weighing things for the consumers.
Rule:- subject + shall have / will have + been + root verb + ing
Examples:
* I shall have been washing my car the whole morning.
* We shall have been playing football in the afternoon.
* You will have been teasing them all day.
* He will have been solving the problems whole morning.
* She will have been sewing loose buttons of my shirt.
* It will have been raining the whole night.
* The sparrows will have been collecting materials for the nests.
* They will have been eating ice-cream in the garden.
* Mary will have been playing with her pretty doll.