+127.+ We find also that we need a verb phrase to express time _before_
some other future time, to describe an action that will be finished,
perfected, or completed, before some other future action. Thus,
I shall have gone before you arrive.
You will have earned your money before you get it.
I shall have worked thirty days when pay-day comes.
Can you not see a difference in saying, _I shall work thirty days when
pay-day comes_, and _I shall have worked thirty days when pay-day
comes_? The first sentence expresses simple future time, or what you
will do when pay-day comes; the second describes an action which will be
completed or perfected _before_ pay-day comes. So there is quite a
difference in the meaning of the future and the future perfect time.
+128.+ +The future perfect time form expresses or describes an action
that will be perfected or completed before some other future time. It is
formed by using _shall have_ or _will have_ with the past
participle.+
Be careful to use the past participle. Never use the past time form with
_shall have_ or _will have_.
+Future Perfect Time+
_Singular_ _Plural_
1st. I shall have seen. We shall have seen.
2d. You will have seen. You will have seen.
3d. He will have seen. They will have seen.