The Present Perfect Continuous is used :

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- when an action started in the past and is still going on and you want to emphasize  the duration of the action (how long it took)

 

Exampe 1: I have been studying English for five years. (and still am)

Example 2: How long have you been studying English at school now? (and still are)

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- when you are irritated 

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Example: I have been waiting for your reply for over a week! (and still are)

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