The perfect continuous aspect

have + been + verb-ing

The perfect continuous is not considered as an aspect in itself; it is rather a combination of the perfect and continuous aspects.

It is expressed with the auxiliaries have and been (the third form of be) and the (present participle) -ing form of the verb. Depending on the time of the action, we use one of the following forms of have: the past (had), present (have, has) or modal + infinitive (e.g. will have).

The perfect continuous expresses that the action had, has or will have been in progress for some time at a specific point in time. This point in time may be defined by a time expression (at 5 o'clock) or a clause (when she gets home).

Examples of the perfect continuous:

I've been waiting for this moment all my life. (from when I was born until now)
He's been ironing his shirts. (from some time in the past until now)
By 2005, George had been living in Scotland for 20 years. (from 1985 to 2005)
When Mary gets home, Kevin will have been sleeping for hours. (Kevin’s sleep lasting from some point in time before Mary gets home until she gets home)
I wouldn't have been sitting there if I hadn't had to. (from some time in the past until a later time in the past)