What does present perfect continous means And why we use verb 3 to do it

The present perfect continuous is used to refer to an unspecified time between 'before now' and 'now'. The speaker is thinking about something that started but perhaps did not finish in that period of time.

You form the present perfect by using “have” or “has” followed by the past participle form of the verb. The present perfect confuses English learners because it refers to a past action. It is also called “present perfect” because speakers use it to stress the importance of a past event in the present.

Answer:
1.The Present Perfect Continuous tense means that it used to describe actions that have started in the past and are now continuing
2.These tenses are also used to describe events that began in the past and have just been completed.

Reason:

Because generally present perfect continuous tense only occurs in the action of dynamic verb, not stative verb because generally only dynamic verb which has continuous form.

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