The present perfect continuous tense shows that an action started in the past, has continued up to the present and is still continuing.
- Alice has been knitting a sweater since morning.
- Scientists have been planning a manned mission to Mars.
- The anxious father has been waiting for a letter from his son.
- We have been waiting for hours.
The question form in this tense will be as follows:
- Have you been waiting for hours? (Have/has + subject + been + present participle + adverbials/complements)
- Has Alice been knitting a sweater?
Since the action started in the past and has been continuing ever since, the only point of time that can be mentioned is such a sentence is the time when the action started.
- He has been working here since 1995.
- She has been waiting for a bus since 8 o’clock.
You can also mention the period of time during which the action has been going on.
- He has been working here for seven years.
- She has been waiting for a bus for one hour.
- We have been working all yesterday. (Wrong)
- We worked all yesterday. (Right)
- It has been raining during the whole of last week. (Wrong)
- It rained during the whole of last week. (Right)