What is it good for?
- Talking about a duration before another action in the future.
- He will have been exercising for more than five hours by the time you arrive.
- They will have been living abroad for nearly ten years by then.
- By the time I get there, you will not have been waiting for more than three hours.
- Talking about the cause of something in the future.
- He will be extremely tired tomorrow because he will have been working for nearly three days without break.
- We will be very hungry because we will have been walking in the woods all day without any snacks.
You can use both will have been or am/are/is going to have been. Both are fine, but I would go with will have been, since it is shorter and a little easier to use.
I will have been traveling for eight months before you meet up with me.
I am going to have been traveling for eight months before you meet up with me.
Making it Negative:
Put not after will or am/are/is. Example: I will not have been singing long by the time you show up. You are not going to have been traveling long before you see the road on the right.
Asking a Question:
Will + subject + have been + present participle (+object)?
Am/Are/Is + subject + going to have been + present participle (+object)?
- Will you have been waiting long by the time I get there?
- Are you going to have been waiting long by the time I get there?
Questions? Ask in the Contact Form or book a class with me to practice!