This tense is used to talk about an action or actions that started in the past and continued until recently or that continue into the future:
We can use it to refer to an action that has finished but you can still see evidence.
- Oh, the kitchen is a mess. Who has been cooking?
- You look tired. Have you been sleeping properly?
- I've got a a stiff neck. I've been working too long on computer.
It can refer to an action that has not finished.
- I've been learning Spanish for 20 years and I still don't know very much.
- I've been waiting for him for 30 minutes and he still hasn't arrived.
- He's been telling me about it for days. I wish he would stop.
It can refer to a series of actions.
- She's been writing to her regularly for a couple of years.
- He's been phoning me all week for an answer.
- The university has been sending students here for over twenty years to do work experience.
The present perfect continuous is often used with 'since', 'for', 'all week', 'for days', 'lately', 'recently', 'over the last few months'.
- I've been wanting to do that for ten years.
- You haven't been getting good results over the last few months.
- They haven't been working all week. They're on strike
- He hasn't been talking to me for weeks.
- We've been working hard on it for ages.
- I've been looking at other options recently.
- He's been working here since 2001.