Present perfect continuous
have/has + been + V+ing
There are two main times we use this tense. Remember we can't use it withstative verbs.
1: To say how long for unfinished actions which started in the past and continue to the present. We often use this with for and since. (See thepresent perfect for the same use with stative verbs)
I've been living in London for two years.
She's been working here since 2004.
We've been waiting for the bus for hours.
2: Actions which have just stopped (though the whole action can be unfinished) and have a result, which we can often see, hear, or feel, in the present (focus on action). (See the present perfect for a similar use which focuses on the result of the action)
I'm so tired, I've been studying.
I've been running, so I'm really hot.
It's been raining, the pavement is wet.
I've been reading your book, it's very good.
Past perfect continuous :
to describe something that happened for a length of time before another action in the past.
had been + V+ing
When I got home, I Was very tired. I'd been working all day.
The town was flooded. It had been raining for three days.
Future Perfect Continuous
to express situations that will last for a specified period of time at a definite moment in the future.
will have been + V+ing
You will have been waitingfor more than two hours when her plane finally arrives.
Will you have been waiting for more than two hours when her plane finally arrives?
You will not have been waiting for more than two hours when her plane finally arrives.