Tenses: Future Perfect

The future perfect expresses an activity that will be completed before another time or event in the future.

1.     I will graduate in June. I will see you in July. By the time I see you, I will have graduated.

2.     I will have finished my homework by the time I go out on a date tonight.

3.     Today is Friday. Mark needs three days to finish his project. By the time you come here next week, he will have finished his project.

4.     We have been married for a long time. By our next anniversary, we will have been married for 43 years.

Note:

By the time introduces a time clause; the simple present is used in a time clause.

Examples of the future perfect in affirmative, negative and interrogative sentences

Affirmative      Tira will have arrived in Japan by 6 a.m. tomorrow.

Negative         Tira won't have arrived in Japan by 6 a.m. tomorrow.

Interrogative    Will Tira have arrived in Japan by 6 a.m. tomorrow?
                       Yes, he will.

                       No, he will not.

* In reference to Understanding and Using English Grammar by Betty Azar