Future Perfect Tense

We use this tense for something that will happen before a specific time or an event in the future or something that will last for a period of time in the future 

Affirmative:SUBJECT+WILL+HAVE DONE+OBJECT

I You He She It We They

will

have eaten

my sandwich.

Negative:SUBJECT+WILL NOT+HAVE DONE+OBJECT

I You He She It We They

will not (won't)

have eaten

my sandwich.

Negative: WILL+SUBJECT+HAVE DONE+OBJECT?

Will

I you he she it we they

have eaten

my sandwich?

                                                                                      

Irene will have finished the project by the evening.                                                      They will have painted the house by Sunday.

                                                                               

By the end of the week, we will have had this car for 10 days.                        Joanna will have perfected her Swedish by the time she moves there.

Time expressions: We generally use this tense with by, by the end of, before, until, till, etc.

Examples:

• By the end of July, I will have known Philippe for 10 years.
• We will have taken her home by midnight.
• There will have made the announcement by the time we get there.
• Louis will have drunk milk before sleep.
• The economy will have grown a big deal by the new fiscal year.