Present Perfect Continuous tense  

It is used to express a continued or ongoing action that started in past and is continued until now. There will be a time reference, such as “since 1980, for three hours etc” from which the action has been started. A sense of time reference is found in these sentences which gives an idea that action has been continued from some time in past till now.  Such time reference or sense of time reference is the identity of Present perfect continuous tense because it tells that action has started from a particular time in past. For example, “He has been reading in this school since 2005”, so the it means that he has started his education in this school in 2005 and he is studying in this school till now.

Note: If there is not time reference or sense of time reference then it is not Present perfect continuous tense because there is no hint about the time of action when it started in past and it seems just an ongoing action at present time which resembles “present Continuous tense. So the reference of time differentiates between Present perfect continuous tense and Present continuous tense.

Rules: An auxiliary verb “has been or have been” is used in sentence. 1st form of verb (base verb) +ing (present participle) is used as main verb in sentence. “Since” or “for” is used before the “time reference” in sentence. If the time reference is exactly known such as 1995, 4 O’clock then “since” is used before the time in sentence. If the time reference is not exactly known such as three hours, six years, four days, then “for” is used before the time in sentence. Time reference such as 3 hours or 5 days is not exactly known because we don’t know that about which three hours a day is told in sentence or about which 5 days in a month is told in sentence. While the 1995 is exactly known time.

Structure of sentence.

Positive Sentence.
• Subject + Auxiliary verb + main verb (Present participle) + Object + Time reference
• Subject + has been/have been + (1st form of verb or base verb + ing) + object +    time reference
If the subject is “He, She, It, singular or proper name” then auxiliary verb “has been” is used after subject in sentence.
If subject is “You, They or plural” then auxiliary verb “have been” is used after subject in sentence.
Examples.
        He has been watering the plants for two hours.
        I have been studying since 3 O’clock

Negative Sentence.
• Subject +”Not” between the Auxiliary verb + main verb (present participle) +     Object + Time reference
• Subject + has not been/have not been + (1st form of verb or base verb + ing) +    object + time reference
To make negative sentence, the word “not” is written between the auxiliary verbs, so it becomes like “has not been or have not been”. The rule for using auxiliary verb “has been or have been” in negative sentences is as same as mentioned above.
Examples.
        He has not been watering the plants for two hours.
        I have not been studying since 3 O’clock.

Interrogative Sentence.
• Auxiliary verb + Subject + Auxiliary verb + main verb (present participle) + object +    time reference
• Has/have + Subject + been + (1st form of verb or base verb+ing) + object + time    reference
Interrogative sentence starts with auxiliary verb. If the subject is “He, She, It, singular or proper name” then the sentence starts with auxiliary verb “has” and auxiliary verb “been” is used after subject
If subject is “You, They or plural” then the sentence starts with auxiliary verb “have” and “been” is used after subject
Examples.
      Has he been watering the plants for two hours?
      Have I been studying since 3 O’clock?

More examples.

Positive sentences
           It has been raining for three days.
           I have been living in America since 2003.
           He has been playing cricket for two hours.
           They have been watching television since 6 O’clock.
           She has been working in this office since 2007.

Negative sentences
         It has not been raining for three days.
         I have not been living in America since 2003.
         He has not been playing cricket for two hours.
         They have not been watching television since 6   
         O’clock.
         She has not been working in this office since 2007.

Positive sentences
        Has it been raining for three days?
        Have I been living in America since 2003?
        Has he been playing cricket for two hours.
        Have they been watching television since 6 O’clock?
        Has she been working in this office since 2007?