The PPT describes an action just completed or an action that’s occurring right before a second event.
Clear as mud? Yeah, me too. I find this stuff confusing when it’s defined, but a little simpler when I see it.
The PPT form is have + been + present participle (ing)
I have been trying to figure out PPT for years, now.
I had been trying to figure out the PPT but then I decided I’d rather eat chocolate.
By this time tomorrow, I will have eaten seven pounds of chocolate while trying to figure out the PPT.