THE PRESENT PERFECT CONTINUOUS TENSE

a. Use :

1. The Present Perfect Continuous tense is used to express continuous, ongoing actions which started in the past and are still going on:

--> I have been cutting the grass.
--> The bus has been waiting for one hour.

The use of the Present Perfect Continuous tense in this example indicates that, at the time of speaking or writing, the bus has completed one hour of waiting. "Waiting" is still on.

2- Present perfect progressive tense lets you show that an action began sometime in the past, continued uninterrupted up to the present, but probably won't continue into the future.

--> I have been telling you all along that you need to brush up on your grammar.
--> She has been trying to get a quote from the mayor all morning.

Both the telling and the trying began sometime in the past. Both actions continued up to the present, but may not continue any more. b. Formation : The Present Perfect Continuous tense of any English verb is formed from the Present Perfect of to be, followed by the present participle of the verb. For instance, the Present Perfect Continuous tense of the verb to work is conjugated as follows:  I have been working  you have been working  he has been working  she has been working  it has been working  we have been working  they have been working Thus, it can be seen that the Present Perfect Continuous tense has two auxiliaries. The first auxiliary is have or has, and the second auxiliary is been. c. Questions and negative statements When a verb has more than one auxiliary, it is the first auxiliary which must change its form to agree with the subject of the verb. It is also the first auxiliary which is used to form questions and negative statements. Questions are formed by placing the first auxiliary before the subject of the verb. For example: Affirmative Statement Question   I have been working.   Have I been working?   You have been working.   Have you been working?   He has been working.   Has he been working?   She has been working.   Has she been working?   It has been working.   Has it been working?   We have been working.   Have we been working?   They have been working.   Have they been working? Negative statements are formed by placing the word not after the first auxiliary. For example: Affirmative Statement Negative Statement   I have been working.   I have not been working.   You have been working.   You have not been working.   He has been working.   He has not been working.   She has been working.   She has not been working.   It has been working.   It has not been working.   We have been working.   We have not been working.   They have been working.   They have not been working. Negative questions are formed by placing the first auxiliary before the subject, and the word not after the subject. However, when contractions are used, the contracted form of not follows immediately after the first auxiliary. For example: Without Contractions With Contractions   Have I not been working?   Haven't I been working?   Have you not been working?   Haven't you been working?   Has he not been working?   Hasn't he been working?   Has she not been working?   Hasn't she been working?   Has it not been working?   Hasn't it been working?   Have we not been working?   Haven't we been working?   Have they not been working?   Haven't they been working?