Grammar

Present Perfect Continuous
(I have been doing)
Have/has been -ing
Have/has been –ing is the present perfect continuous:
Present perfect continuous
The present continuous describes what a person is doing.
The present perfect continuous tells how long a person has been doing that action.

Ex. Katie is delivering mail.
She has been delivering mail for two hours.
she has been working for the post office since 1997.
Present perfect continuous
The present perfect continuous talks about an action that started in the past and continues in the present. The action is not yet complete. It tells how long the action has been in progress.
He has been washing windows since 8:00.

They have been waiting for the bus for twenty minutes.
Present perfect continuous
Since & For
You can use the present perfect continuous for
actions that are repeated over a period of time:

Debbie is a very good tennis player. She’s been playing since she was eight.
Every morning they meet in the same café. They’ve been going there for years.
For and since
For shows an amount of time.
for three hours
for ten days

Since tells when an action started
since 2:00
since he came to the United States
For and since
SINCE
FOR
I am doing vs. I have been doing
Compare I am doing and I have been doing:
How long has she been looking for a job?

How long have they been living in the city?
How long questions
We use the present perfect (especially with how long, for, and since) to talk about something that began in the past and still continues now. Compare the present and the present perfect:

We know each other very well.
but We’ve known each other since we were in high school.
(not We know)
Do you have a pain in your stomach?
but How long have you had the pain?
(not How long do you have)
I’m learning English.
but I’ve been learning English for six months.
(not I am learning)
He’s waiting for somebody.
but He’s been waiting all morning.
How long have you (been)…?
How long have you (been)…?
I have known/had/lived, etc., is the present perfect simple.
I have been learning/been waiting/been doing, etc., is the present perfect continuous.
In most situations with how long, since, and for, the continuous is more usual:

I’ve been studying English for six months. (more usual than I’ve studied)
It’s been raining since lunchtime.
Richard has been doing the same job for 20 years.
“How long have you been driving?” “Since I was 17.”
But some verbs (for example, know/like/believe) are not normally used in the continuous:
How long have you known Jane?
(not have you been knowing)

You can use either the present perfect continuous or present perfect simple with live and work:
John has been living / has lived in Denver for a long time.
How long have you been working / have you worked here?

But we use the simple (I’ve done / I’ve lived, etc.) with always:
John has always lived in Denver. (not has always been living)

We use the present perfect simple in negative sentences like these:
I haven’t seen Tom since Monday.
(= Monday was the last time I saw him)
Jane hasn’t called me for two weeks.
(= the last time she called was two weeks ago)