Present perfect continuous tense is used when we would like to express something happened that was began in the past time and still continue to the present time and we do not know if it still happens in the future. In other words, there is a relation that indicates duration of an activity which is began in the past time till now.
From here, we can see that there are three main points in the tense that we have to know:
- Activity in the past time
- Present Activity
- Possibililty in the future
Past event was began > Budi did his homework yesterday.
At a time of speaking > Now he is still doing it.
Possibility > We do not know if he will finish his homework one or two seconds in the future or not.
Look at this following illustration!
Preposition for is usually used in the present perfect continuous tense. This indicates duration (past > present).
I have been doing this homework for 2 days.
Since is used to indicates when an event of an activity occurs in the first time or when it began.
I have been doing this homework since yesterday.
Study this following sentence structure of Present perfect continuous tense:
(+) Subject + have/has + been + present participle or the -ing form verb.
e.g. She has been doing hes duty for two hours.
(-) Subject + have/has + not + been + present participle or the -ing form verb. *)
e.g. She has not been doing hes duty for two hours.
(?) Subject + have/has + been + present participle or the -ing form verb.
e.g. Has she been doing hes duty for two hours ?
Sample of further question:
How long has she been doing her duty?
*) Notice that we can use /have not/ or /haven't/ and /has not/ or /hasn't/. Whether it is has or have, depends on the subject! Have is for I, You, We and They ... Has is for She, He or It.