Future Perfect Continuous Sentence

Explanation

When I graduate from university, I will have
been studying for ten years.

I am studying now. I am going to graduate in the future. I will
continue to study until I graduate. The total amount of time I
will spend studying is ten years.

By the time Sharon finishes the triathlon, she will
have been exercising for four hours.

Sharon will be exercising for four hours continuously. She will
be exercising in the future. The total amount of time she will
be exercising is four hours.

I was wrong. Michael will not have been driving for
eight hours when he arrives. He will have
been driving for twelve hours!

Michael will drive for twelve hours continuously. He will be driving
in the future. The total amount of time he will be driving is twelve
hours.

Is it really true? Will you have
been living together for five years this fall?

The people are living together now. In the future (the fall) they
will still be living together. The time spent living together will
equal five years.
